Poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) belongs to a class of thermally stable engineering plastics. The present article describes the various structural modifications carried out on PPO to achieve certain special properties. Thermal properties of these modified polymers do not change much as compared to parent PPO; however, their solubility characteristics exhibit unusual trends. The broad range of solvents available for modified PPO enhances the possibility of casting PPO based membranes for use in membrane separation processes.