Size-controlled cadmium sulphide nanoparticles (CdS) stabilized by mercaptoethanol layers were prepared in solution and successively dispersed into different poly(vinyl alcohol)-based polymer matrices. The absorption and the emission features of the CdS nanocomposites were found to differ from those of colloidals dispersions and to be mainly affected by the particle (loose) aggregation in phase-separated, particle-rich regions of the materials. It was also found that the optical behaviour of the nanocomposites can be modulated through uniaxial orientation, which is presumed to partially destroy the aggregations. (c) 2008 Elsevier Ltd. All rights reserved.