The present invention describes a barrier layer composition which is applied to at least one surface of a plastic body, preferably a polyolefin hollow body, having the following composition:(a) 35 to 75% by weight of an epoxide-containing or halogen- and epoxide-containing metal oxide sol;(b) 20 to 60% by weight of a fluorine- or sulfo-containing maleic acid hemi ester copolymer or a fluorine- or sulfo-containing maleic acid hemi amide copolymer having the general structural formula ##STR1## wherein M=vinyl monomer; X=oxygen, nitrogen;Y=--(CH.sub.2).sub.n --SO.sub.3 H, --(CH.sub.2).sub.n --F, --(CF.sub.2).sub.n --H;n=2 to 12;(c) 0.5 to 5% by weight of a catalyst based on one or more tertiary amines.