In the demethylation of 6-hydroxy-3, 4', 7-trimethoxy-5-tosyloxyflavone (1) with anhydrous aluminum bromide (AlBr3) or anhydrous aluminum chloride-sodium iodide (AlCl3-NaI) in acetonitrile, the elimination of the 5-tosyloxy group proceeded after demethylation to give 8-bromo-3, 6, 7-trihydroxy-4'-methoxyflavone (6) or 3, 6, 7-trihydroxy-4'-methoxyflavone (5) as a main product. The demethylation of 6-hydroxy-4', 7-dimethoxy-5-tosyloxyflavone (2) with AlCl3-NaI also afforded 6, 7-dihydroxy-4'-methoxyflavone (12), but that with AlBr3 afforded 8-bromo-5, 6, 7-trihydroxy-4'-methoxyflavone (13) as a main product. The demethylation of 1 with anhydrous aluminum chloride (AlCl3) was accompanied by migration of the tosyl group to give a mixture of 3, 6-dihydroxy-7, 4'-dimethoxy-5-tosyloxyflavone (3) and 5-hydroxy-3, 4', 7-trimethoxy-6-tosyloxyflavone (9), but that of 2 proceeded after the cleavage of the 5-tosyloxy group to give a mixture of 5, 6-dihydroxy-7, 4'-dimethoxy- (14) and 5, 6, 7-trihydroxy-4'-methoxyflavones (15) other than the corresponding 6-tosyloxyflavone (16). In the demethylation of the acetates of 1 and 2 with AlCl3, the cleavage of the 5-tosyloxy group proceeded prior to the demethylation to afford the corresponding 5, 6, 7-trihydroxyflavones (8 and 15), although the demethylation of the former acetate was accompanied by formation of 3, 5, 7-trihydroxy-4'-methoxy-6-tosyloxyflavone (10). Mechanisms are proposed for these reactions.