TiO2 nanoparticles/melamine Tri sulfonic acid (MTSA) supported on silica gel as an efficient catalytic system for simple, one pot, solvent-free and environmentally benign process for synthesis of dihydropyrimidines via Biginelli reaction at 110 °C is described. It was found that the catalyst is reusable and exhibited remarkable activity. The catalyst can be easily separated and reused several t...