This paper reports a facile synthesis of magnetically separable iron oxide (gamma-Fe2O3) nanoparticles using thermolysis method. The structural and morphological study of the synthesized gamma-Fe2O3 nanopartides was carried out using X-ray diffraction (XRD), field emission gun-scanning electron microscopy (FEG-SEM), energy dispersive X-ray spectrum (EDS), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS) techniques. The electron microscopy reveals that the gamma-Fe2O3 nanoparticles have spherical morphology with a particle size in the range of 40-100 nm. The XPS study confirmed the Fe is in +3 oxidation state. The synthesized gamma-Fe2O3 nanoparticies have been used as an efficient heterogeneous catalyst for the organic transformation between phenols, alcohols, and amines with acetic anhydride under sonication using mild reaction conditions. Various electrons withdrawing and electrons donating substrates show an excellent yield of desired products with the advantage of magnetic separation and reusability of gamma-Fe2O3 nanocatalyst. (C) 2015 Elsevier B.V. All rights reserved.