An efficient and straightforward procedure for the synthesis of 1,8-dioxo-dodecahydroxanthene was achieved through one-pot condensation of arylaldehyde and 1,3-cyclohexanedione in the presence of polyaniline-p-toluienesulfonate salt as polymeric solid acid catalyst. For the first time it is demonstrated that polyaniline salt could be used as catalyst in aqueous medium also. This method provides several advantages such as easy synthesis, simple work up, versatility, reusability. (c) 2005 Elsevier B.V. All rights reserved.