In this paper the photoelectrochemical processes occurring in composites formed of organic-capped CdS nanocrystals and low molecular weight poly [2-methoxy-5-(2'-ethyl-exyloxy)phenylene vinylene] conjugated polymer were investigated. High quality colloidal CdS nanoparticles were synthesized by means of thermal decomposition of suitable precursors in non coordinating solvents, using oleic acid as surface capping agent. The absorption and emission properties of the prepared heterojunctions were studied both in solutions and in composite films. The dispersed hybrids were also investigated as photoactive materials, focusing on the photoinduced charge transfer and recombination processes at the interface between the two components. The composites have shown a fundamental role in photoelectrochemical applications due to the presence of a great number of interfaces able to enhance the charge transfer between mixture components. Blend solutions prepared with octylamine capped CdS nanocrystals showed an improvement of the photoconductivity with respect to hybrids containing longer oleate surfactants. (C) 2008 Elsevier B.V. All rights reserved.