TK6 was able to produce NAD+ dependent cyclohexanol dehydrogenase(CDH). The production of CDH was increased rapidly at the logarithmic phase and maintained constantly after that. In order to investigate the inductive production of CDH by various substrates, the bacteria were grown in the media containing alicyclic hydrocarbons and various alcohols as a sole crabon souce. CDH was induced most actively by cyclohexanol. Cyclohexanone and cyclohexane-1,2-diol also induced remarkable amount of CDH but it was induced weakly by 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, 2-propanol, and 2-methyl-1-propanol. The dehydrogenase of the bacteria grown in the media containing cyclohexanol were weakly active for various alcohols, but the dehydrogenase activity for cyclohexane-1,2-diol was twice as much as that for cyclohexanol. Activity staining on PAGE of the cell free extract of Rhodococcus sp. TK6 grown in the media containing cyclohexanol reveals at least sever isozyme bands of CDH and we nominated the four major activity bands as CDH I, II, III, and IV. CDH I was strongly induced by cyclohexanol, cyclohexane-1,2-diok, but its activity was specific to cyclohexane-1,2-diol and 1-pentanol. CDH IV was strongly induced by cyclohexanol and cyclohexane-1,2-diol, and its activity was very specific to cyclohexane-1,2-diol.