ZrOCl 28H 2O supported on montmorillonite K10 (ZrOCl 2/mont K10) catalyzed Biginelli reaction under solvent-free conditions is reported. The catalysts were characterized by XRD, FTIR, BET surface area analysis, and thermogravimetric analysis. The activity of montmorillonite K10, montmorillonite KSF, ZrOCl 28H 2O, SO 4 2-/ZrO 2, and ZrOCl2/mont K10s was investigated by Biginelli reaction of benzaldehyde, ethylacetoacetate and urea. The reactions were carried out by addition of ZrOCl 2/mont K10 to a mixture of aldehyde, ethylacetoacetate and urea/thiourea with thorough stirring in the absence of solvent under conventional heating or microwave irradiation to prepare 3,4- dihydropyrimidin-2(1H)-one/thione derivatives at 80 °C in good yields. © Springer Science+Business Media, LLC 2011.