Indium (III) chloride (InCl3) and metaphosphoric acid ((HPO3)n) were found to be efficient and recyclable catalysts for the synthesis of 1,8-dioxooctahydroxanthene derivatives as biologically important molecules in high turnover numbers and rates. Several substituted xanthenes can be prepared in high yield and purity by direct reaction of cyclic B-diketones and aldehyde derivatives in the presence of a catalytic amount of InCl3 and (HPO3)n as Lewis acids and at ambient temperature under solvent-free conditions. This newly reported procedure profit some advantages such as short reaction times, high yields of products, cheap, easy to use, facile practical conditions, and wholesome with green chemistry without using harmful solvents.