Polymerization catalyst systems, their production and use

A process of polymerizing olefins alone or in combination with one or more other olefins, the process comprising polymerizing in the presence of a supported catalyst system formed by the steps of:

• a) introducing a porous inorganic carrier to a vessel having a starting pressure;
• b) depressurizing the vessel;
• c) introducing into the vessel a solution comprising a metallocene catalyst component and an activator while maintaining the depressurized pressure from step (b);
• d) pressurizing the vessel;
• and
• e) recovering the supported catalyst system;
• wherein steps (a) and (b) are performed before step (c).