The degradation of alkylcyclohexane by Acinetobacter sp. ODDK71 was investigated. Strain ODDK71 degraded alkylcyclohexanes (alkyl side chain length of greater than or equal to12) by co-metabolism when hexadecane was used as a growth substrate. GC/MS analysis of co-metabolized products from dodecylcyclohexane suggests that strain ODDK71 degraded dodecylcyclohexane via a ring oxidation and an alkyl side chain oxidation pathways. The ring oxidation pathway of dodecylcyclohexane is a novel pathway of microbial degradation of dodecylcyclohexane.