gamma-Fe2O3 nanoparticles (NPs) were synthesized from a single-source precursor complex [Fe3O(C6H5-COO)(6)(H2O)(3)[NO3 by a simple thermal decomposition process and have been characterized by X-ray diffraction analysis (XRD), transmission electron microscopy (TEM) and UV-vis spectroscopic techniques. The NPs were highly pure and well crystallized having hexagonal morphology with an average particle size of 35 nm. The prepared gamma-Fe2O3 (maghemite) NPs show effective photo-catalytic activity toward the degradation of rose bengal (RB) and methylene blue (MB) dyes under visible light irradiation and can easily be recoverable in the presence of magnetic field for successive re-uses. The possible photo-catalytic decomposition mechanism is discussed through the detection of hydroxyl radical (OH center dot) by terephthalic acid photo-luminescence probing technique. (C) 2013 Elsevier Ltd. All rights reserved.