In this paper, large scale CdS nanospheres are synthesized via a facile and effective hydrothermal route. Through an inspection of the morphologies under various growth conditions, a possible growth mechanism for CdS nanospheres was proposed, which involves a nuclei aggregation and an Ostwald ripening process. The as- prepared CdS nanospheres exhibit superior photocatalytic activities by the photodegradation of eosin red, Congo red (CR) and methylene blue (MB) under visible light irradiation, with a comparison with the other CdS nanostructures, P25 and alpha-Fe2O3 powders. It demonstrates potential applications in removal of organic dye molecules from waste water. (C) 2014 Elsevier B.V. All rights reserved.