The catalytic activity of the transition metals and their compounds is ascribed to:

The catalytic property of transition metals is due to -their tendency to form reaction intermediates with suitablereactants. These intermediates give reaction paths of lower activation energy and, therefore, increase the rate of the reaction.These reaction intermediates readily decompose yielding the products and regenerating the original substance. The transition metals form these reaction intermediates due to the presence of vacant orbitals or their tendency to form variable oxidation states.