diff --git a/news/deprecate-lattice.rst b/news/deprecate-lattice.rst
@@ -0,0 +1,25 @@
+**Added:**
+
+* Added ``set_latt_parms`` method into ``Lattice`` class
+* Added ``set_new_latt_base_vec`` method into ``Lattice`` class
+
+**Changed:**
+
+* <news item>
+
+**Deprecated:**
+
+* Deprecated ``setLatPar`` method in ``Lattice`` class for removal in version 4.0.0
+* Deprecated ``setLatBase`` method in ``Lattice`` class for removal in version 4.0.0
+
+**Removed:**
+
+* <news item>
+
+**Fixed:**
+
+* <news item>
+
+**Security:**
+
+* <news item>
diff --git a/src/diffpy/structure/expansion/supercell_mod.py b/src/diffpy/structure/expansion/supercell_mod.py
@@ -82,7 +82,7 @@ def supercell(S, mno):
     newS.__setitem__(slice(None), newAtoms, copy=False)
 
     # take care of lattice parameters
-    newS.lattice.setLatPar(a=mno[0] * S.lattice.a, b=mno[1] * S.lattice.b, c=mno[2] * S.lattice.c)
+    newS.lattice.set_latt_parms(a=mno[0] * S.lattice.a, b=mno[1] * S.lattice.b, c=mno[2] * S.lattice.c)
     return newS
 
 

diff --git a/src/diffpy/structure/lattice.py b/src/diffpy/structure/lattice.py
@@ -27,6 +27,22 @@
 import numpy.linalg as numalg
 
 from diffpy.structure.structureerrors import LatticeError
+from diffpy.utils._deprecator import build_deprecation_message, deprecated
+
+base = "diffpy.structure.Lattice"
+removal_version = "4.0.0"
+setLatPar_deprecation_msg = build_deprecation_message(
+    base,
+    "setLatPar",
+    "set_latt_parms",
+    removal_version,
+)
+setLatBase_deprecation_msg = build_deprecation_message(
+    base,
+    "setLatBase",
+    "set_new_latt_base_vec",
+    removal_version,
+)
 
 # Helper Functions -----------------------------------------------------------
 
@@ -168,37 +184,37 @@ class Lattice(object):
 
     a = property(
         lambda self: self._a,
-        lambda self, value: self.setLatPar(a=value),
+        lambda self, value: self.set_latt_parms(a=value),
         doc="The unit cell length *a*.",
     )
 
     b = property(
         lambda self: self._b,
-        lambda self, value: self.setLatPar(b=value),
+        lambda self, value: self.set_latt_parms(b=value),
         doc="The unit cell length *b*.",
     )
 
     c = property(
         lambda self: self._c,
-        lambda self, value: self.setLatPar(c=value),
+        lambda self, value: self.set_latt_parms(c=value),
         doc="The unit cell length *c*.",
     )
 
     alpha = property(
         lambda self: self._alpha,
-        lambda self, value: self.setLatPar(alpha=value),
+        lambda self, value: self.set_latt_parms(alpha=value),
         doc="The cell angle *alpha* in degrees.",
     )
 
     beta = property(
         lambda self: self._beta,
-        lambda self, value: self.setLatPar(beta=value),
+        lambda self, value: self.set_latt_parms(beta=value),
         doc="The cell angle *beta* in degrees.",
     )
 
     gamma = property(
         lambda self: self._gamma,
-        lambda self, value: self.setLatPar(gamma=value),
+        lambda self, value: self.set_latt_parms(gamma=value),
         doc="The cell angle *gamma* in degrees.",
     )
 
@@ -323,12 +339,12 @@ def __init__(
         # work out argument variants
         # Lattice()
         if not argset:
-            self.setLatPar(1.0, 1.0, 1.0, 90.0, 90.0, 90.0, baserot)
+            self.set_latt_parms(1.0, 1.0, 1.0, 90.0, 90.0, 90.0, baserot)
         # Lattice(base=abc)
         elif base is not None:
             if len(argset) > 1:
                 raise ValueError("'base' must be the only argument.")
-            self.setLatBase(base)
+            self.set_new_latt_base_vec(base)
         # Lattice(lat)
         elif isinstance(a, Lattice):
             if len(argset) > 1:
@@ -339,10 +355,10 @@ def __init__(
             abcabg = ("a", "b", "c", "alpha", "beta", "gamma")
             if not argset.issuperset(abcabg):
                 raise ValueError("Provide all 6 cell parameters.")
-            self.setLatPar(a, b, c, alpha, beta, gamma, baserot=baserot)
+            self.set_latt_parms(a, b, c, alpha, beta, gamma, baserot=baserot)
         return
 
-    def setLatPar(
+    def set_latt_parms(
         self,
         a=None,
         b=None,
@@ -441,7 +457,34 @@ def setLatPar(
         self.isotropicunit = _isotropicunit(self.recnormbase)
         return
 
+    @deprecated(setLatPar_deprecation_msg)
+    def setLatPar(
+        self,
+        a=None,
+        b=None,
+        c=None,
+        alpha=None,
+        beta=None,
+        gamma=None,
+        baserot=None,
+    ):
+        """This function has been deprecated and will be removed in
+        version 4.0.0.
+
+        Please use diffpy.structure.Lattice.set_lat_par instead.
+        """
+        return self.set_latt_parms(a, b, c, alpha, beta, gamma, baserot)
+
+    @deprecated(setLatBase_deprecation_msg)
     def setLatBase(self, base):
+        """This function has been deprecated and will be removed in
+        version 4.0.0.
+
+        Please use diffpy.structure.Lattice.set_lat_base instead.
+        """
+        return self.set_new_latt_base_vec(base)
+
+    def set_new_latt_base_vec(self, base):
         """Set new base vectors for this lattice.
 
         This updates the cell lengths and cell angles according to the

diff --git a/src/diffpy/structure/parsers/p_discus.py b/src/diffpy/structure/parsers/p_discus.py
@@ -201,7 +201,7 @@ def _parse_cell(self, words):
         words = self.line.replace(",", " ").split()
         latpars = [float(w) for w in words[1:7]]
         try:
-            self.stru.lattice.setLatPar(*latpars)
+            self.stru.lattice.set_latt_parms(*latpars)
         except ZeroDivisionError:
             emsg = "%d: Invalid lattice parameters - zero cell volume" % self.nl
             raise StructureFormatError(emsg)

diff --git a/src/diffpy/structure/parsers/p_pdb.py b/src/diffpy/structure/parsers/p_pdb.py
@@ -157,7 +157,7 @@ def parseLines(self, lines):
                     alpha = float(line[33:40])
                     beta = float(line[40:47])
                     gamma = float(line[47:54])
-                    stru.lattice.setLatPar(a, b, c, alpha, beta, gamma)
+                    stru.lattice.set_latt_parms(a, b, c, alpha, beta, gamma)
                     scale = numpy.transpose(stru.lattice.recbase)
                 elif record == "SCALE1":
                     sc = numpy.zeros((3, 3), dtype=float)
@@ -171,7 +171,7 @@ def parseLines(self, lines):
                     scaleU[2] = float(line[45:55])
                     base = numpy.transpose(numpy.linalg.inv(sc))
                     abcABGcryst = numpy.array(stru.lattice.abcABG())
-                    stru.lattice.setLatBase(base)
+                    stru.lattice.set_new_latt_base_vec(base)
                     abcABGscale = numpy.array(stru.lattice.abcABG())
                     reldiff = numpy.fabs(1.0 - abcABGscale / abcABGcryst)
                     if not numpy.all(reldiff < 1.0e-4):

diff --git a/src/diffpy/structure/parsers/p_xcfg.py b/src/diffpy/structure/parsers/p_xcfg.py
@@ -253,7 +253,7 @@ def parseLines(self, lines):
                 emsg = ("%d: auxiliary fields are " "not consistent with entry_count") % p_nl
                 raise StructureFormatError(emsg)
             # define proper lattice
-            stru.lattice.setLatBase(xcfg_H0)
+            stru.lattice.set_new_latt_base_vec(xcfg_H0)
             # here we are inside the data block
             p_element = None
             for line in ilines:

diff --git a/tests/test_lattice.py b/tests/test_lattice.py
@@ -44,7 +44,7 @@ def test___init__(self):
         self.assertRaises(ValueError, Lattice, 1, 2, 3)
         self.assertRaises(ValueError, Lattice, 1, 2, 3, 80, 90)
         L0 = self.lattice
-        L0.setLatBase(L0.cartesian([[1, 1, 0], [0, 1, 1], [1, 0, 1]]))
+        L0.set_new_latt_base_vec(L0.cartesian([[1, 1, 0], [0, 1, 1], [1, 0, 1]]))
         L1 = Lattice(L0)
         self.assertTrue(numpy.array_equal(L0.base, L1.base))
         L2 = Lattice(base=L0.base)
@@ -77,6 +77,28 @@ def cosd(x):
         self.assertAlmostEqual(cosd(120.0), dot(base[0], base[1]) / (1 * 2), self.places)
         return
 
+    def test_set_lat_par(self):
+        """Check calculation of standard unit cell vectors."""
+        from math import cos, radians, sqrt
+
+        from numpy import dot
+
+        def norm(x):
+            return sqrt(sum([xi**2 for xi in x]))
+
+        def cosd(x):
+            return cos(radians(x))
+
+        self.lattice.set_latt_parms(1.0, 2.0, 3.0, 80, 100, 120)
+        base = self.lattice.base
+        self.assertAlmostEqual(1.0, norm(base[0]), self.places)
+        self.assertAlmostEqual(2.0, norm(base[1]), self.places)
+        self.assertAlmostEqual(3.0, norm(base[2]), self.places)
+        self.assertAlmostEqual(cosd(80.0), dot(base[1], base[2]) / (2 * 3), self.places)
+        self.assertAlmostEqual(cosd(100.0), dot(base[0], base[2]) / (1 * 3), self.places)
+        self.assertAlmostEqual(cosd(120.0), dot(base[0], base[1]) / (1 * 2), self.places)
+        return
+
     def test_latpar_properties(self):
         """Check assignment to a, b, c, alpha, beta, gamma."""
         lat = self.lattice
@@ -152,9 +174,9 @@ def test_setLatBase(self):
         self.assertAlmostEqual(detR0, 1.0, self.places)
         # try if rotation matrix works
         self.assertEqual(numpy.all(base == self.lattice.base), True)
-        self.lattice.setLatPar(alpha=44, beta=66, gamma=88)
+        self.lattice.set_latt_parms(alpha=44, beta=66, gamma=88)
         self.assertNotEqual(numpy.all(base == self.lattice.base), True)
-        self.lattice.setLatPar(alpha=60, beta=60, gamma=60)
+        self.lattice.set_latt_parms(alpha=60, beta=60, gamma=60)
         self.assertTrue(numpy.allclose(base[0], self.lattice.base[0]))
         self.assertTrue(numpy.allclose(base[1], self.lattice.base[1]))
         self.assertTrue(numpy.allclose(base[2], self.lattice.base[2]))
@@ -171,6 +193,39 @@ def test_setLatBase(self):
         )
         return
 
+    def test_set_lat_base(self):
+        """Check calculation of unit cell rotation."""
+        base = numpy.array([[1.0, 1.0, 0.0], [0.0, 1.0, 1.0], [1.0, 0.0, 1.0]])
+        self.lattice.set_new_latt_base_vec(base)
+        self.assertAlmostEqual(self.lattice.a, numpy.sqrt(2.0), self.places)
+        self.assertAlmostEqual(self.lattice.b, numpy.sqrt(2.0), self.places)
+        self.assertAlmostEqual(self.lattice.c, numpy.sqrt(2.0), self.places)
+        self.assertAlmostEqual(self.lattice.alpha, 60.0, self.places)
+        self.assertAlmostEqual(self.lattice.beta, 60.0, self.places)
+        self.assertAlmostEqual(self.lattice.gamma, 60.0, self.places)
+        detR0 = numalg.det(self.lattice.baserot)
+        self.assertAlmostEqual(detR0, 1.0, self.places)
+        # try if rotation matrix works
+        self.assertEqual(numpy.all(base == self.lattice.base), True)
+        self.lattice.set_latt_parms(alpha=44, beta=66, gamma=88)
+        self.assertNotEqual(numpy.all(base == self.lattice.base), True)
+        self.lattice.set_latt_parms(alpha=60, beta=60, gamma=60)
+        self.assertTrue(numpy.allclose(base[0], self.lattice.base[0]))
+        self.assertTrue(numpy.allclose(base[1], self.lattice.base[1]))
+        self.assertTrue(numpy.allclose(base[2], self.lattice.base[2]))
+        # try base checking
+        self.assertRaises(
+            LatticeError,
+            self.lattice.set_new_latt_base_vec,
+            [[1, 0, 0], [1, 0, 0], [0, 0, 1]],
+        )
+        self.assertRaises(
+            LatticeError,
+            self.lattice.set_new_latt_base_vec,
+            [[1, 0, 0], [0, 0, 1], [0, 1, 0]],
+        )
+        return
+
     def test_reciprocal(self):
         """Check calculation of reciprocal lattice."""
         r1 = self.lattice.reciprocal()
@@ -185,7 +240,7 @@ def test_reciprocal(self):
     def test_dot(self):
         """Check dot product of lattice vectors."""
         L = self.lattice
-        L.setLatPar(gamma=120)
+        L.set_latt_parms(gamma=120)
         self.assertAlmostEqual(-0.5, L.dot([1, 0, 0], [0, 1, 0]), self.places)
         va5 = numpy.tile([1.0, 0.0, 0.0], (5, 1))
         vb5 = numpy.tile([0.0, 1.0, 0.0], (5, 1))
@@ -199,14 +254,14 @@ def test_norm(self):
         self.assertEqual(1, self.lattice.norm([1, 0, 0]))
         u = numpy.array([[3, 4, 0], [1, 1, 1]])
         self.assertTrue(numpy.allclose([5, 3**0.5], self.lattice.norm(u)))
-        self.lattice.setLatPar(gamma=120)
+        self.lattice.set_latt_parms(gamma=120)
         self.assertAlmostEqual(1, self.lattice.norm([1, 1, 0]), self.places)
         return
 
     def test_rnorm(self):
         """Check norm of a reciprocal vector."""
         L = self.lattice
-        L.setLatPar(1, 1.5, 2.3, 80, 95, 115)
+        L.set_latt_parms(1, 1.5, 2.3, 80, 95, 115)
         r = L.reciprocal()
         hkl = [0.5, 0.3, 0.2]
         self.assertAlmostEqual(r.norm(hkl), L.rnorm(hkl), self.places)
@@ -217,7 +272,7 @@ def test_rnorm(self):
     def test_dist(self):
         """Check dist function for distance between lattice points."""
         L = self.lattice
-        L.setLatPar(1, 1.5, 2.3, 80, 95, 115)
+        L.set_latt_parms(1, 1.5, 2.3, 80, 95, 115)
         u = [0.1, 0.3, 0.7]
         v = [0.3, 0.7, 0.7]
         d0 = numalg.norm(L.cartesian(numpy.array(u) - v))
@@ -235,7 +290,7 @@ def test_angle(self):
         from math import acos, degrees
 
         L = self.lattice
-        L.setLatPar(1, 1.5, 2.3, 80, 95, 115)
+        L.set_latt_parms(1, 1.5, 2.3, 80, 95, 115)
         u = [0.1, 0.3, 0.7]
         v = [0.3, 0.7, 0.7]
         uc = L.cartesian(u)
@@ -254,12 +309,12 @@ def test_repr(self):
         """Check string representation of this lattice."""
         r = repr(self.lattice)
         self.assertEqual(r, "Lattice()")
-        self.lattice.setLatPar(1, 2, 3, 10, 20, 30)
+        self.lattice.set_latt_parms(1, 2, 3, 10, 20, 30)
         r = repr(self.lattice)
         r0 = "Lattice(a=1, b=2, c=3, alpha=10, beta=20, gamma=30)"
         self.assertEqual(r, r0)
         base = [[1.0, 1.0, 0.0], [0.0, 2.0, 2.0], [3.0, 0.0, 3.0]]
-        self.lattice.setLatBase(base)
+        self.lattice.set_new_latt_base_vec(base)
         r = repr(self.lattice)
         self.assertEqual(r, "Lattice(base=%r)" % self.lattice.base)