Abstract: A fibrous catalyst comprises at least one transition metal anchored to a polymer fibre having a plurality of grafted units grafted to a polymer backbone. The polymer backbone may be a polyolefin, a fluorinated polyethylene, cellulose or viscose. The grafted units comprise a salt of a carboxylic acid, which in a preferred embodiment is a sodium salt of acrylic acid. The catalysts are particularly suitable for scavenging oxygen from sealed packages or containers and may further comprise a chemical indicator for the presence or absence of oxygen.