Photo catalytically active Cu7S4 thin films on Fluorine doped Tin Oxide (FTO) coated glass substrates were successfully prepared using a simple, low-cost electrochemical technique (Galvanic technique), providing an economic way of obtaining nanostructured Cu7S4 thin films. The deposited films were characterized by its optical, structural and morphological properties. XRD pattern of the as-deposited Cu7S4 thin film shows monoclinic phase. UV-vis spectral analysis of the film gives direct band-gap of 1.95 eV. The FESEM images show uniform distribution of spherical crystallites with compactly packed needle shaped nano-grains. The additional roughness was achieved in the nano-grain like morphology. The needle shaped nano-grains interact efficiently with the dye molecules and results in a strong photo catalytic degradation of Rose-Bengal (RB) dye. Effect of thickness on the photocatalytic degradation performance was studied and linear increase in rate constant values with thicknesses was obtained. (C) 2014 Elsevier B.V. All rights reserved.