A hydrosilation process is dislosed for the reaction between silicon-hydrogen bonds and compounds having aliphatic carbon atoms linked by multiple bonds using as catalysts novel platinum-nitrogen complex compounds of the following classes:(a) monometallic complexes, (L)PtX.sub.2 (Y),(b) bimetallic complexes, (L)(PtX.sub.2).sub.2 (Y).sub.2,(c) ionic complexes, (L)PtX.sub.2 (Y)(Z), and(d) reduced forms of said monometallic complexes having the formulae:H[(PNZ)PtX.sub.2 (Q)].sub.2, (1)[(PNZ)PtX.sub.2 (Q)].sub.2.sup.- A.sup.+, (2) and[H(PNZ)PtCl.sub.2 (C.sub.2 H.sub.4)].sub.3 PtCl.sub.3 (3) whereinL is a single or fused ring unsaturated heterocyclic ligand, wherein said hetero atoms are nitrogen, comprising at least one 5- or 6-member ring, said ligand having 2 to 4 nitrogen atoms in the same ring, and said ligand having up to a total of 44 carbon atoms,Y is an uncharged olefinically unsaturated hydrocarbon monodentate ligand that fills only one coordination position of the platinum atom and is selected from olefinically unsaturated hydrocarbons, triarylphosphines or triarylarsines wherein aryl is phenyl or phenyl substituted by up to 4 lower alkyl groups having 1 to 4 carbon atoms, dialkyl sulfides wherein each alkyl group independently has 1 to 16 carbon atoms, and carbon monoxide, the ligand having up to 25 carbon atoms,X is independently Cl, Br, I, CN, or SCN,Z is HCl, HBr, or silver trifluoromethanesulfonate,Q is an aliphatically unsaturated olefin ligand of 2 to 25 carbon atoms,A is a cation, andPNZ is phenazine.Preparation of the novel catalysts is described. The cured compositions are useful in the preparation of molded articles.