Abstract: The methods of RRDE and cyclic voltammetry have been used to study the oxidation of cysteine on heat-treated cobalt tetramethoxyphenyl porphyrin adsorbed on graphic (Co-TMPP/graphine); Experimental results show that Co-TMPP/graph-ite exhibits signigicant catalytic activity for cysteine oxidation in solutions of different pHvhues. The current efficiency of the cysteine oxidation on Co-TMPP/graph-ite is more than 90%. Cysteine oxidation is a simple charge transfer irreversible reaction on Co-TMPP/graphiic. The standard rate constants (k°) of the cysteine oxiJation were calculated and the reac:ion mechanism of cysteinc oxida-tion were discussed in solutions of various pH.