Direct ortho-acylation of phenol and naphthol derivatives with organic acids smoothly proceeded in the presence of various Lewis acids and microwave irradiation under atmospheric conditions. This method is a new, easy and clean reaction for preparation of ortho-hydroxyaryl ketones in excellent yields with high regioselectivity into substitution of acyl group in ortho situation. These reactions have some advantages in competition with other methods such as; short reaction times, high yield and regioselectivity of products, mild reaction conditions, ease the workup of reactions. (c) 2006 Elsevier B.V. All rights reserved.