PURPOSE:To avoid hydrolysis of functional group of cyclohexenes and obtain the title compound in high conversion and yield by reacting cyclohexenes with an oxygen-containing gas in the presence of a secondary alcohol using a cobalt complex as a catalyst. CONSTITUTION:A compound expressed by formula II (R and R are H, alkyl, etc.; R to R are H, alkyl, CN, etc.) is subjected to oxidation and reduction reaction using a catalyst [e.g., bis(2,4-pentanedionate)cobalt(II)] expressed by formula I [R , R , R and R are alkyl, aryl, perfluoroalkyl, CO2R or CO2 NR R (R is alkyl or aryl; R and R are H, alkyl or aryl, etc.), except when R , R , R and R are CF3 and R and R are H] in the presence of a secondary alcohol to provide cyclohexanols and/or cyclohexanones. Also in cyclohexenes having a functional group such as CN or CO2CH3, functional group thereof is free from hydrolysis.