The invention relates to a process for the preparation of a metal-organic compound, comprising at least one phosphinimine ligand, characterized in that the HA adduct of a phosphinimine ligand according to formula (1) is contacted with a metal-organic reagent of formula (2) in the presence of 1, respectively 2 equivalents of a base, wherein HA represents an acid, of which H represents its proton and A its conjugate base, with Y.dbd.N--H as formula (1), and M.sup.v(L.sub.1).sub.k(L.sub.2).sub.l(L.sub.3).sub.m(L.sub.4).sub.nX as formula (2), and wherein Y is a substituted phosphorous atom, and M represents a group 4 or group 5 metal ion, V represents the valency of the metal ion, being 3, 4 or 5 L.sub.1, L.sub.2, L.sub.3, and L.sub.4 represent a ligand or a group 17 halogen atom on M and may be equal or different, k, l, m, n=0, 1, 2, 3, 4 with k+l+m+n+1=V, and X represents a group 17 halogen atom. The invention further relates to a process for the preparation of a polyolefin by making a metal-organic compound according to the process of the invention, wherein the base is an olefin polymerization compatible base, which metal-organic compound is activated anywhere in, or before a polymerization reactor.