We study the bulk radical polymerization of methyl methacrylate (MMA) in the presence of bis(1,1,5,5-tetraethyl-2,4-dithiobiureto)cadmium(II) [Cd(N(SCNEt2)(2))(2)] (TEDBCd) used as the precursor of CdS nanoparticles. This compound is readily soluble both in MMA monomer and in polymethyl methacrylate (PMMA). The bulk samples based on PMMA containing up to 7% of this cadmium compound are visually transparent and colorless. We study thermal and optical properties of the obtained composites. UV irradiation of bulk composites based on the PMMA matrix with TEDBCd results in the formation of luminescent pattern containing CdS nanoparticles, which is proved by TEM and HRTEM analysis.