The polyelectrolyte-surfactant complex DHP-PDDA was prepared by reacting the anionic surfactant dihexadecylphosphate (DHP) with polycationic poly(diallyldimethylammonium) (PDDA). Thin films made from DHP-PDDA on solid substrates demonstrated an ordered multibilayer structure by XRD and DSC. Incorporated myoglobin (Mb) in DHP-PDDA films on pyrolytic graphite (PG) electrodes showed a pair of well-defined and nearly reversible cyclic voltammetric peaks for the Mb Fe(III)/Fe(II) couple at about -0.3 V vs SCE in pH 7.0 buffers. Electron transfer between Mb and PG electrodes was greatly facilitated in the film microenvironment. The positions of the Soret absorption band suggest that Mb maintains its secondary structure similar to its native state in DHP-PDDA films in the medium pH range. Mb could act as an enzyme-like catalyst in DHP-PDDA films as demonstrated by catalytic reduction of trichloroacetic acid, nitrite, and oxygen with a decrease in the electrode potentials required. Mb-DHP-PDDA films may thus have potential application as biosensors. Copyright 2001 Academic Press.