The immobilization of monolayers and submonolayers of glucose oxidase on carbon electrodes by adsorption of rabbit IgG (antigen) and reaction with a glucose oxidase conjugated antibody, the antirabbit IgG produced in goat, is described. As revealed by radioactive I-125 labeling and by cyclic voltammetry, using ferrocene methanol as mediator, the enzyme monolayers thus immobilized are fully active and persistent. The fact that the mediator couple remains reversible in the presence of the enzyme film allows a particularly simple and quick derivation of primary and secondary plots characterizing the enzyme kinetics from the cyclic voltammetric responses. Comparison with chemically derivatized electrodes investigated in the same manner under similar conditions shows the superiority of the immunological attachment technique.