An enzyme electrode is constructed and optimized for inhibitor determination. The urease electrode inhibited by fluoride ions is chosen as an example to illustrate the procedure. The enzyme is chemically bound with glutaraldehyde to a silicone membrane which is a part of the CO2 gas electrode. The inhibition reversibility is tested and various parameters related to the enzyme cross-linking technique are studied separately. The theoretical and experimental behaviors of the enzyme electrode as a function of inhibitor concentration are compared by analyzing the steady-state substrate and product concentration profiles inside the active layer. This study defines the optimum operating conditions for the use of an enzyme electrode.