diff --git a/Cantera/python/Cantera/SurfacePhase.py b/Cantera/python/Cantera/SurfacePhase.py
index aed3669e7..24c424891 100644
--- a/Cantera/python/Cantera/SurfacePhase.py
+++ b/Cantera/python/Cantera/SurfacePhase.py
@@ -11,12 +11,15 @@ class SurfacePhase(ThermoPhase):
         ThermoPhase.__init__(self, xml_phase=xml_phase, index=index)
 
     def setSiteDensity(self, n0):
+        """Set the site density."""
         _cantera.surf_setsitedensity(self._phase_id, n0)
 
     def siteDensity(self):
+        """Site density [kmol/m2]"""
         return _cantera.surf_sitedensity(self._phase_id)
     
     def setCoverages(self, theta):
+        """Set the surface coverages to the values in array 'theta'."""
         nt = len(theta)
         if nt == self.nSpecies():
             _cantera.surf_setcoverages(self._phase_id,
@@ -26,12 +29,16 @@ class SurfacePhase(ThermoPhase):
                                ' coverage values, but got '+`nt`)
 
     def coverages(self):
+        """Return the array of surface coverages."""
         return _cantera.surf_getcoverages(self._phase_id)
 
-    def setConcentrations(self, theta):
-        _cantera.surf_setconcentrations(self._phase_id, theta)
+    def setConcentrations(self, conc):
+        """Set the surface concentrations to the values in
+        array 'conc'."""
+        _cantera.surf_setconcentrations(self._phase_id, conc)
 
     def concentrations(self):
+        """Return the array of surface concentrations [kmol/m2]."""
         return _cantera.surf_getconcentrations(self._phase_id)