Capillary zone electrophoresis was employed for the analysis of cytochromecusing an end-column amperometric detector with a L-cysteine-modified gold microdisk array electrode. The optimum conditions of separation and detection are 0.04 mol/L KH2PO4- 0.06 mol/L Na2HPO4for the buffer solution, 8 kV for the separation voltage, 4 kV and 10 s for the injection voltage and the injection time, and −0.12 V vs. SCE for the detection potential. When the fused-silica capillary modified by ethylene glycol was used, the adsorption of cytochromecon the surface of the capillary wall could be overcome. The limit of detection is 3 × 10−5mol/L or 62 fmol (S/N = 2). The method was applied to determining cytochromecin pig heart.