Studies on aldol reactions of benzaldehyde with a thioketene silyl acetal in water in the presence of various dodecyl sulfate and dodecanesulfonate salts as Lewis acid-surfactant combined catalysts have revealed that the order of the catalytic ability of these salts at the initial stage of the reaction is Cu > Zn, Ag > Sc, Yb > Na > Mn, Co salts, and that the Sc and Yb salts afforded the aldol product in more than 90% final yields due to their ability to suppress the hydrolysis of the thioketene silyl acetal.