A process which comprises reacting a 1,2,3,4-cyclobutane- tetracarboxylic-1,2:3,4-dianhydride [1] with an alcohol [2] in the presence of an acid catalyst to obtain a compound [3], isomerizing the compound [3] with a base catalyst into a compound [4], reacting the compound [4] with an organic acid to obtain a compound [5], and reacting the compound [5] with a dehydrating agent to obtain a 1,2,3,4-cyclobutanetetracarboxylic-1,3:2,4 -dianhydride: wherein R¹ and R² are each independently hydrogen, halogeno, alkyl of 1 to 10 carbon atoms, halogenated alkyl of 1 to 10 carbon atoms, cycloalkyl of 3 to 8 carbon atoms, phenyl, or cyano; and R³ is alkyl of 1 to 10 carbon atoms.