A process for the polymerization of at least one olefin comprising reacting said at least one olefin with a catalyst comprising: (i) a metallocene complex said metallocene comprising at least two cyclopentadienyl type ligands; (ii) a boron cocatalyst; and (iii) an aluminoxane cocatalyst; said catalyst being in solid form, preferably in solid particulate form, and being free from an external carrier.