A magnetic species was synthesized in a 100 mL Teflon-lined stainless steel autoclave at 180 degrees C for 10 h. The synthesized species was characterized by powder X-ray diffraction, transmission electron microscopy, scanning electronic microscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy and vibrating sample magnetometry at room temperature. The results showed that the synthesized species was nickel ferrite nanoparticles with diameters of approximately 10 nm. The nanoparticles exhibited a photo-Fenton catalytic feature for the degradation of rhodamine B in the presence of oxalic acid. The effects of pH, oxalic acid concentration, and dosage of the catalyst, on the degradation rates of the dyes were examined. The optimal degradation rate was reached with 1.0 mM oxalic acid at pH 3.0. Seven cyclic tests for rhodamine B degradation showed that the magnetic catalyst was very stable, recoverable, highly active, and easy to separate using an external magnet. Hence, this magnetic catalyst has potential use in organic pollutant removal. (C) 2012 Elsevier B.V. All rights reserved.