The invention provides a stabilising composition for polymeric materials comprising: at least one secondary arylamine having the formula I: wherein: the R or each R, may be the same or different, independently denotes an optionally substituted hydrocarbyl group having at least 5 carbon atoms; x and y are each independently from 0 to 5 provided that at least one of x and y is at least 1; and a phenolic antioxidant, the composition and/or the secondary arylamine being a liquid at ambient conditions substantially free from diphenylamine and/or from lower alkylated diphenylamine antioxidants.