PhOMe was acylated with Ac2O to p-AcC6H4OMe in MeNO(3) on acidified and optionally calcinated synthetic zeolite, montmorillonite and bentonite clays at 95 C for 3 h to compare the catalytic activity of the solid Friedel-Crafts catalysts. The highest conversion was achieved when montmorillonite and zeolite catalysts were used (38% and 35%, resp.). The catalyst activity decreased rapidly during the reaction. Traces of polycyclic compds. and small amts. of o-AcC(6)H(4)OMe (1-2%) were found in the reaction products.