The present disclosure provides a polyester polymer product which contains partially or fully cobalt-neutralized organic sulphonic acid component and which is substantially free of ether and its preparation. The present disclosure also provides an oxygen scavenging composition made from a mixture of the polyester polymer product of the present disclosure, an organic oxidizable polymeric component and optionally at least one additional polyester component. The present disclosure further provides a packaging article defined by walls having an oxygen transmission rate (OTR) less than 0.2 cc·m−2 day−1 at 0.28 mm thickness and its preparation.