A new and efficient method has been developed for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones/thiones (DHPMs) through Biginelli reaction in aqueous media. Furthermore, a new series of N-dihydro pyrimidinone-decahydroacridine-1,8-diones (8a-m) have been synthesized by the Hantzsch reaction of 5-Ethoxycarbony1-4-(4-aminophenyl)-6-methyl-3,4-dihydropyrimidine-2(1H)-one 5 (DHPM), with dimedone and aromatic aldehyde in acetonitrile under reflux conditions. All the products in both reactions obtained in good to excellent yields by proceeding through a simple and efficient procedure employing cellulose sulfuric acid (CSA) as a recyclable solid acid catalyst. All the newly synthesized compounds structure has been established by advanced spectroscopic data. (C) 2013 Elsevier B.V. All rights reserved.