Cadmium sulfide thin films have been electrodeposited by a method involving the application of a square wave potential to tin oxide electrodes immersed in an electrolyte containing cadmium sulfate and sodium thiosulfate. To elucidate the main electrodic processes that occur during the positive and negative parts of the applied wave, a voltammetric study has been carried out. The morphology and the structural and optical properties of these films are analyzed. Electrical properties before and after annealing are reported.