Abstract The surface of Fe3O4 magnetic nanoparticles was modified with silica shell and copper containing poly(melamine-terephthaldehyde) through a facile and efficient method. The structure of these nanoparticles was characterized by using the following techniques: Fe-SEM, TGA/DTA, XRD, FTIR, VSM, BET, EDS and XPS. Then, this compound was used as a magnetic, reusable and heterogeneous nano-catalyst for the synthesis of benzimidazole derivatives. The represented method proved that this novel material could show great catalytic performance and produce the desired products with high purity and excellent yields in short times. The efficiency of this catalyst was also compared with the catalysts which were previously reported for the synthesis of benzimidazoles. It was clear from this comparison that our catalyst was distinguished from the previous ones due to its inherent magnetic properties so this compound can be one of the best catalysts for the synthesis of benzimidazoles. The other advantages of the represented procedure include simple conditions, environmentally friendliness, high recovery ability, easy work-up and low cost.