In this work, the behaviour of P3MeTh films in aqueous solutions is characterized by cyclic voltammetry under chopped light in the potential domain where the polymer is oxidized, as well in its reduced state. The photocurrent observed in the negative potential region is enhanced by the incorporation of copper particles in the polymer matrix and subsequent oxidation, resulting in a PSMeTh/Cu2O photosensitive composite. The electrochemical photocurrent displayed by the polymer and by the composite are discussed under the light of classic formalisms derived from solid state theory and of a recent model proposed by Semenikhin et al. which appears to describe well this type of modified electrodes.