Polyoxyphenylenes were obtained from phenol, 2-methylphenol, 2,5-dimethyl-phenol in oxidative polycondensations using dimethylpyridineCuCl complexes as catalysts. Samples of polymers from polycondensations were not completely linear as found by i.r. analysis. The m.s. and c.c.—m.s. analysis of degradation products of poly(2-methylphenylene oxide) (PMPO) and poly(2,5-dimethylphenylene oxide) (P2, 5DMPO) have shown that both polymers undergo Fries-type rearrangement prior to statistical scission of benzyl bonds. Ether linkages of poly(1,4-phenylene oxide) (PPO) decompose without rearrangement though cyclization to benzofurane systems has been observed.