Salicylic acid is obtained in good to excellent yield by carboxylation of phenol with a carbon dioxide in the presence of Lewis acid catalysts at moderate temperatures (293-353 K). Among the catalysts investigated, aluminium bromide (AlBr3) was found to be the most active. To optimize the reaction conditions and study the reaction mechanism, the experimental variables including the various Lewis acids, temperature, carbon dioxide pressure, amount of AlBr3, chlorotrimethylsilane additive, etc. were studied. Under the optimized conditions, nearly complete carboxylation of phenol to salicylic acid was observed with 10 mmol of AlBr3 added to an autoclave. On the basis of experimental findings, the most feasible reaction mechanism proposed involves the formation of an organoaluminium-like compound. Crown Copyright (c) 2008 Published by Elsevier B.V. All rights reserved.