Polypyrrole (PPy) films containing cobalt tetrasulphonated phthalocyanine (CoTsPc) were electrosynthesized at gold electrodes by cyclic voltammetry. Oxygen reduction at the cobalt phthalocyanine modified polypyrrole gold electrodes (Au/PPy/CoTsPc) was investigated mainly in acid solutions because of the non-conductivity of the polymer matrix in alkaline electrolytes. The number of electrons transferred during the oxygen reduction was determined using the rotating disk electrode technique. The ability of the Au/PPy/CoTsPc electrode to reduce hydrogen peroxide to water was also investigated. It is shown that several mechanisms, depending on the potential, may be involved in oxygen reduction at such electrodes. For potentials greater than 0.4 V(RHE), the mechanism involved two exchanged electrons and the main product formed was hydrogen peroxide, while for potentials lower than 0.4 V(RHE), four electrons were transferred during oxygen reduction, giving water as the main product.