US and CdSe nanoparticles were prepared in organic solvents using as templates inverse amphiphilic block copolymer micellar aggregates, which were induced by. cadmium complexation. Amphiphilic block copolymers utilized in this work include poly(sulfonated styrene-block-tert-butylstyrene) (SPS-PtBS) and poly(styrene-block-sulfonated isoprene) (PS-SPI). Copolymers with different compositions and molecular weights were synthesized by anionic polymerization high-vacuum techniques and postpolymerization selective sulfonation reactions. Cadmium acetate was used as the cadmium precursor and thioacetamide or H2Se as the sulfur or selenium source, respectively. The nanostructured organic-inorganic hybrid materials were characterized in solution and in thin films by light scattering, UV-vis and fluorescence spectroscopy, infrared and Raman vibrational spectroscopy, and transmission electron microscopy (TEM). The influence of composition and molecular weight of block copolymers on the properties of nanoparticles was investigated at all stages of nanoparticle formation. It was shown that well-defined CdS and CdSe semiconductor nanoparticles with controllable sizes and optical properties can be formed by judicious choice of the experimental conditions following the suggested prepdration protocol.