A new magnetically separable catalyst consisting of phosphotungstic acid (PTA) supported on imidazole functionalized silica coated cobalt ferrite nanoparticles was prepared. The synthesized catalyst was characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), thermogravimetric analysis (TGA), Fourier transform infrared (FT-IR), and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The immobilized phosphotungstic acid was shown to be an efficient heterogeneous catalyst for the synthesis of alpha-aminophosphonates under solvent-free conditions at room temperature. The catalyst is readily recovered by simple magnetic decantation and can be recycled several times with no significant loss of catalytic activity. (C) 2013 Elsevier B.V. All rights reserved.