A series of poly[ethylene-co-bis(2-ethoxy)hydroquinone terephthalate], PET-co-BEHQ copolymers were prepared by polymerization of various substituted bis(2-hydroxyethyl)hydroquinones (BEHQs), dimethyl terephthalate (DMT), and ethylene glycol (EG). In addition to copolymers containing 6-16.5 mol % BEHQ the homopolymer of BEHQ with dimethyl terephthalate, p(BEHQ-T), was also prepared. The thermal and barrier properties of amorphous materials were studied. As the amount of comonomer was increased, the T-g and T-m of the materials decreased relative to those of PET. Oxygen permeability also decreased with increasing comonomer content. This improvement in barrier-to-oxygen permeability was primarily due to a decrease in solubility of oxygen in the polymer. All of the copolymers tested displayed similar oxygen diffusion coefficients. The decrease in solubility correlates with the decrease in T-g. (C) 2003 Wiley Periodicals, Inc.