Ordered films were made by casting a mixture of aqueous dispersions of didodecyldimethylammonium bromide (DDAS)-clay composite and myoglobin (Mb )solution on pyrolytic graphite (PG)electrodes The Mb-DDAB-clay film electrodes showed stable and reversible cyclic voltammetric responses in buffers and can catalyze the reduction of trichloroacetric acid(TCA) Ordered films were made by casting a mixture of aqueous dispersions of didodecyldimethylammonium bromide (DDAS) -clay composite and myoglobin (Mb) solution on pyrolytic graphite (PG) electrodes The Mb-DDAB-clay film electrodes showed stable and reversible cyclic voltammetric responses in buffers and can catalyze the reduction of trichloroacetric acid (TCA)