Disclosed is a process for isomerizing cis-2-pentenenitrile to 3-pentenenitrile in the presence of a non-aluminum metal oxide catalyst, wherein: (a) the metal in the catalyst has an oxidation state in the range from +1 to +4; (b) the metal has a cation radius in the range from 0.35 to 1.0 Å; (c) the metal of the catalyst has a polarizing power, C/r, is in the range from 2 to >8, wherein C is the charge of the metal and r is the ionic radius in Å; (d) the bond network of the catalyst has a % ionicity of >20; (e) the metal oxide has an acidity strength in the range from strong to very weak; and (f) the metal oxide has a basicity (nucleophilicity) strength of weak to strong.