Cytochrome c oxidase immobilized in lipid bilayer membranes on gold electrodes mediates electron transfer between reduced cytochrome c in solution and the electrode. Under flow conditions, fixed potential amperometry of anaerobic solutions of reduced cytochrome c shows changes in the rate of enzyme mediated electron transfer from cytochrome c to oxidase modified electrodes. These data are consistent with literature that describes both activation of the resting oxidase state to the pulsed oxidase state and subsequent decay of the pulsed oxidase state to the resting oxidase state.