In this research, a magnetically-recoverable catalyst (NiFe2O4@SiO2–H3PMo12O40) was prepared by supporting phosphomolybdic acid (H3PMo12O40) onto silica-coated NiFe2O4 nanoparticles. The prepared sample was characterized by FT-IR, TEM, SEM and VSM techniques and then the catalytic activity of this catalyst was investigated in the synthesis of tri- and tetra-substituted imidazole derivatives. More importantly, the catalyst was easily isolated from the reaction mixture by a magnetic bar and reused at least ten times without significant degradation in its activity.
