A process for the preparation of a silicon containing transition metal compound that includes the steps of (a) non-hydrolytic sol-gel condensation of a silane of formula L.sub.xSiQ.sub.n wherein L is a .sigma.-bonded ligand, Q is an anionic ligand, and x+n=4 with a halogenated silane (or siloxane) and an alkoxysilane, (b) optionally alkylation, (c) deprotonation and (d) addition of a transition metal compound. The process allows for the preparation of transition metal compounds which may suitably be used with cocatalysts for the polymerization of olefins, in particular for such processes carried out in the gas phase.