[en] The composition and catalytic properties of catalysts obtained in ethylene polymerization due to interaction of zirconium halogen substituted allyl complexes of Zr(C₃H₅)sub(4-n)Xsub(n) composition (where n=1,2; X=Cl, Br, J) with silica gel dehydroxylated at different temperatures are investigated by infra-red spectroscopy and viscosimetry. It is established that the nature and number of nonorganic anions bound with a zirconium ion in the active centre, essentially effect the catalyst activity and molecular weight of the forming polymer