The present invention relates to a process for the manufacture of compounds comprising two nitrile functional groups. It relates more particularly to a process for the manufacture of dinitrile compounds from compounds comprising a nitrile functional group and an ethylenic unsaturation in the presence of a catalytic system comprising an organometallic complex and a cocatalyst of the Lewis acid type. The process of the invention comprises a stage of treatment of the reaction medium resulting from the hydrocyanation which makes it possible to extract and recover the metal element of the Lewis acid.