The construction of electrodes, the behavior of which could be accurately analyzed and optimized is described. Two methods were used to construct such enzyme electrodes. A direct binding method, where a cation electrode was dipped into a solution of enzyme, albumin, and glutaraldehyde: a thin layer of cross-linked protein coated the electrode bulb. A two-step method, where an active membrane was first made by cross-linking these proteins by glutaraldehyde on a glass plate, then fitting with a silicone membrane onto a gas electrode (O2 or CO2). Both methods were used to construct glucose and urease electrodes measuring either NH4+ ions or CO2. Glucose oxidase and L-amino acid oxidase-pO2 electrodes were also developed. The theoretical and experimental behavior of these enzymatic membrane electrodes were compared using the analysis of product concentrations resulting from the association of diffusion with enzyme reaction in the active layer, and the optimum operating conditions were determined.