Abstract: A method of preparing a poly(arylene ether ketone) having a repeat unit ##STR1## comprising polymerizing a monomer system comprising (I) a monomer of the formula ##STR2## and (II) a monomer of the formula ##STR3## wherein R.sup.1 is p-phenylene, m-phenylene, or 4,4'-biphenylene;R.sup.2 is p-phenylene, m-phenylene, biphenylene, or naphthylidene; andX is a group displaceable under Friedel-Crafts polymerization conditions;in a polymerization medium comprising(a) a Lewis base present in an amount between about 0.05 and about 2 equivalents per equivalent of acid halide groups present in the monomer system and(b) a Lewis acid present in an amount of at least one equivalent per equivalent of carbonyl groups present, plus an equivalent per equivalent of Lewis base present, plus an amount effective to act as a catalyst for the polymerization.