In this paper, large scale hierarchical CdS dendrites are synthesized via a facile and effective hydrothermal route. The morphologies, microstructures and photocatalytic properties of the as-synthesized products are investigated in detail. Individual CdS dendrites consist of a long central trunk with secondary and tertiary sharp branches, which preferentially grow in a parallel direction with a definite angle to the trunk. A possible growth mechanism for CdS dendrites is proposed based on the experimental results and phenomena. Photocatalytic tests reveal that eosin red can be degraded nearly completely (over 95%) after visible light irradiation of 100 min. In addition, Congo red and methylene blue aqueous solution degradation experiments are also conducted under the same conditions, revealing versatile potential applications of such dendritic structures for wastewater purification.