Complexes of group VIII metals in low oxidation numbers react in solution with fullerene to yield structurally ill-defined compounds with reproducible compositions and properties. A variety of characterisation methods (analysis, XRD, FT-IR, TPD) indicate that the transition metals are located in the interstices of the fullerene lattice being distorted bit the volume of the complexes with partly coordinated residual ligands. The fullerene molecules complete the coordination shells of these catalytically active materials.