Biginelli reaction is the most well-known and widely studied multicomponent reaction used for the direct synthesis of many biologically active 3,4-dihydropyrimidinones or thiones and their derivatives by reacting a beta-keto ester/1,3-dicarbonyl compound, an aldehyde, and urea/thiourea. A new easily recoverable solid catalyst, Nafion-Ga (Gallium Nafionate, Ga(III) salt of Nafion-H, a solid polymeric perfluoroalkanesulfonic acid) was prepared from Nafion-K by metal exchange. Nafion-Ga is found to be an efficient and environmentally benign catalyst for the Biginelli reaction. A series of 3,4-dihydropyrimidinones and thiones were conveniently prepared by this green protocol using the catalyst under solvent free conditions. The wide scope of the catalyst for many other acid catalyzed organic transformations can be ascertained by further screening studies.