The “in situ” formation of cadmium sulphide in a polyethylene oxide matrix has been studied starting with its complex with cadmium chloride. It has been found that the complex crystallizes in orthorhombic configuration with lattice parameters of a = 8.42 Å, b = 15.39 Å and c = 18.49 Å, and that its morphology is spherulitic. At high concentrations (>1:4 per monomer), the added salt gets excluded out of the spherulites and deposits in the interspherulitic regions. The cadmium sulphide formed from such a complex has mixed α and β phases and its crystallite/particle size depends on the initial concentration of the cadmium chloride.