ABSTRACT 	Carbon paste electrodes were modified with cytochrome c reductase enzyme. The behavior of the electrodes was characterized by cyclic voltammetry. The cytochrome c reduction was investigated both on the enzyme modified carbon paste electrode and in a homogeneous system. In the first case, a significant electrocatalytic effect on the reduction of cytochrome c was found. The effect is supported by an increase of 4.3 fold of the peak current and a shift of the cathodic peak potential toward less cathodic values. Also, apparent Michaelis constant values were calculated. 	Results from this work show that carbon paste electrode modified by the cytochrome c reductase represents a new interface that will permit the study of electron transfer reactions involved in biodegradation processes.