Four supported metallocenes prepared by the sol-gel method were tested by ethylene homopolymerization and in ethylene/1-hexene copolymerization. The effects of Al/Zr ratio, polymerization temperature and cocatalysts were evaluated. Catalyst A2, produced by TEA and MAO treatments showed the highest activity (180 x 10(3) kg PE/mol Zr h(-1)) among the tested systems at Al/Zr = 1000. A2 showed thermal stability on polymerization performed at a temperature as high as 120 degreesC. All the systems exhibited activity in the presence of common alkylaluminum (TMA, TEA, TIBA). Comonomer effect was observed in the copolymerization of ethylene with l-hexene, where the comonomer incorporation is about 7 mol%. SAXS measurements of the employed xerogel suggested a weakly branched polymeric texture. Metal content in the resulting polymers showed extremely low levels of Zr. (C) 2001 Elsevier Science Ltd. All rights reserved.