An efficient and simple method for the preparation of -aryl-3,4,5,6,7,9-hexahydroxanthene-1,8-diones from 1,3-cyclohexadione and several aldehydes in the presence of supercritical diethylether has been developed. The present method has several advantages such as excellent yields, relatively short reaction time (60 min), simple work-up procedure, and the use of a cheap solvent. Experiments were also performed in subcritical water. However, subcritical water is not found a proper reaction media for the synthesis of xanthenediones. (C) 2015 Elsevier B.V. All rights reserved.