Strong metal support interaction with supported group VIII metals is associated with the phase transformation of the support employed. The reduced uptake of hydrogen and the enhanced reactivity in CO hydrogenation in these systems are associated with the geometrical dispersion of the metal species, which is identified to have arisen from the formation of a ternary oxide phase and its subsequent reorganization under high temperature reduction conditions. XPS experimental evidence is provided for this postulate. © 1995 Chapman & Hall.