Use of a catalyst composition treated with a surface modifier in the polymerization of olefins for lowering the gel content in the resulting polyolefin, wherein the surface modifier has a polar residue capable of interacting with the surface of the catalyst composition and a lipophilic residue and is selected from carboxylate metal salts, nitrogen containing catalyst surface modifiers, phosphorus containing catalyst surface modifiers, oxygen containing catalyst surface modifiers, sulfur containing catalyst surface modifiers, fluoro containing polymeric catalyst surface modifiers or mixtures thereof and wherein the gel content is determined by using pressed plate gel analysis method.