The metabolic thermogenesis curves of mitochondria isolated from Oryctolagus cuniculus domestica liver tissue have been determined by using an LKB-2277 bioactivity monitor. After isolation, mitochondria maintain activity when stored in appropriate nutrients. The thermokinetic equation: [formula: see text] was established for the activity recovery phase of metabolism. For these studies, the order of metabolism was found to be zero. The metabolic activity of mitochondria was inhibited by humic acid, a potential toxicant in Kashin-Beck and Keshan diseases. Experimental results indicate that humic acid will effect the heat output and lag time of mitochondrial metabolism.