Department of Chemistry, University of Delhi. Delhi-7 Manuscript received 34) August 1973; revised 21 December 1973; accepted 13 March 1974 The two isomeric 1-carboxy-4-methylcyclohexane-1-acetic acids have by a series of reactions been converted into their respective 4-methylcyclohesane-1, 1-dicarboxylic acids and their identities confirmed by their unambiguous synthesis.