Direct and regioselective carboxylation of fused aromatic compounds with carbon dioxide is achieved with the aid of a Lewis acid. Thus, treatment of naphthalene, anthracene, and phenanthrene with carbon dioxide (3.0 MPa) in benzene at 40degreesC in the presence of AlBr3 gave 1-naphthoic acid, 9-anthracenecarboxylic acid, and 9-phenanthrenecarboxylic acid as the sole acid product in 43, 20, and 34% yields, respectively.