Thermally induced polymerization of diazoketones, (E)-1-diazo-3-nonen-2-one 1 and (E)-1-diazo-4-phenyl-3-buten-2-one 2, is described. Heating 1 and 2 in a solvent at 60-100 degrees C afforded polymers, where all the main chain carbons bear acyl groups derived from the monomers and the main chain contains ca. 25-35 mol% of azo group. Molecular weight of the resulting polymers increased up to M-n = 8,400 by the addition of benzoquinone to the reaction mixtures. The polymerization was supposed to proceed via radical propagating chain end and copolymerization of 1 with styrene gave copolymers (M-n = 11,000-15,000) having acylmethylene, azo group, and repeating unit from styrene in their main chains.