The voltammetry of cytochrome c oxidase immobilized in lipid bilayer membranes on gold electrodes and amperometric data of cytochrome c reacting at these electrodes under flow conditions are reported. A submonolayer of octadecyl mercaptan formed on electrodeposited silver anchors and becomes a part of the lipid bilayer membrane on the gold electrode. The supported lipid bilayer membrane containing cytochrome c oxidase is formed during a deoxycholate dialysis procedure. Slow scan rate cyclic voltammograms (20 mV/s) taken at the oxidase-modified electrodes show well-defined anodic waves. Fast scan rate cyclic voltammograms (200 mV/s) taken at the oxidase-modified electrodes show well-defined anodic and cathodic waves. Cyclic voltammograms taken at the oxidase-modified electrodes under 0.1 mM sodium cyanide show an increase (ca. 300%) in electrode capacitance and well-defined anodic and cathodic waves irrespective of scan rate, The voltammetric data are consistent with electron transfer of cytochrome c oxidase coupled with changes in nonfaradaic current and possibly diffusion of cytochrome c oxidase in a lipid multilayer structure. Quartz crystal microbalance data of cytochrome c binding to lipid bilayer membranes containing no cytochrome c oxidase under flow conditions are presented.