In this study, aluminosilicate MCM-41 has been found to be an efficient catalyst for reaction between different benzaldehyde derivatives and 5,5-dimethyl-1,3-cyclohexanedione to give open chain analogue of 1,8-dioxo-octahydroxanthene in excellent yields. No evidence for the formation of cyclization products was observed. The catalyst can be used several times after recovery.