To provide a catalyst compsn. which is prepd. by causing a specific silica carrier to support a catalyst useful for preparing polyketones, does not cause polymer staining due to the residual carrier and hence dispenses with the step of separating the silica carrier from the final product.

This catalyst compsn. comprises (A) a catalyst suitable for preparing polyketones and supported by (B) a silica having hydroxyl-functional groups. Pref., the catalyst contains a metal compd. of the group VIII (pref. iron, cobalt, nickel, or ruthenium) and also contains at least one ligand (pref. phosphorus, arsenic, or antimony) which can coordinate with a group VIII metal. Silica as the carrier pref. has a particle size lower than 100 μm and a hydroxyl content of 0.5-3 mmol. Pref., the catalyst compsn. further contains a Broensted acid or a Lewis acid as a cocatalyst.