Brønsted acidic 1-ethyl-1,2,4-triazolium phenylsulfonate has been synthesized and characterized. A catalytic study is performed for 1-ethyl-1,2,4-triazolium phenylsulfonate as acid catalyst for a multicomponent reaction of synthesis of series of 3,4-dihydropyrimidin-2(1H)-ones/thiones and their derivatives have been employed and the results were discussed in detail.