Various nonyl 3-substituted-dithiocarbazates, methyl and dimethyl derivatives of nonyl 3-benzoyldithiocarbazate, nonyl 2-substituted-dithiocarbamates, and benzaldehyde nonyldithiocarbohydrazone were synthesized and their uncoupling activities of oxidative phosphorylation in mitochondria were examined. The results indicate that the presence of the thiocarbamoyl structure with the potential SH group is a requisite for uncoupling activity. The presence of a C=O group and a hydrophobic aromatic ring significantly increases the uncoupling activity.