Synthesis of 3,4-dihydropyrimidinones/thiones, a multicomponent synthesis using ethyl acetoacetate, substituted aromatic aldehydes, and urea/thiourea has been carried out in presence of Mg-Al-CO3 and Ca-Al-CO3 hyclrotalcite as a reusable solid catalyst. The work has been carried out under thermal solvent-free conditions without microwave irradiations, and under microwave irradiation. In this method excellent yield of 3,4-dihydropyrimidinones/thiones is reported in shorter duration. Hydrotalcites are non-toxic, easy to separate and recyclable catalyst hence making this process environment friendly. Mechanistic study of the reaction using hydrotalcites as catalyst has been studied under thermal conditions without microwave irradiations. (C) 2011 Elsevier B.V. All rights reserved.