Small palladium and platinum clusters have been synthetized within a purely hydrocarbon polymer matrix. The procedure consists of ring-opening metathesis polymerisation of norbornene-derived organometallic complexes, Pd(Cp N )(PA) and Pt(Cp N )Me 3 (Cp N = endo-2-(cyclopentadienylmethyl)norbon-5-ene and PA = η 3 -1-phenylallyl), using W or Mo alkylidene initiators, followed by static casting of films and subsequent reduction of the organometallic complexes under mild conditions using molecular hydrogen