The invention concerns a method for hydrocyanation of ethylenically unsaturated organic compounds into compounds comprising at least a nitrile function. More particularly, it concerns a method for hydrocyanation of organic compounds comprising at least a ethylenical bond by reacting hydrogen cyanide, in the presence of a catalytic system comprising a transition metal and an organophosphorus ligand. The organophosphorus ligand is a compound with monophosphanorbornadiene structure. The invention concerns in particular hydrocyanation of butadiene into adiponitrile.