The catalytic isomerization reaction of 2-methyl-3-butenenitrile (2M3BN) into 3-pentenenitrile (3PN) has been performed in the presence of Ni(0) and phosphine complexes and in biphasic ionic liquid/organic solvent. Several neutral and ionic phosphines and ionic liquids have been tested, the best results for the reaction of isomerization in conversion, selectivity, and immobilization of the catalyst in the ionic liquid phase have been obtained with the (m-sulfophenyl)-diphenylphosphine sodium salt, [TPPMSNa] as ligand and 1-butyl-2,3-dimethylimidazolium-bis(trifluoromethylsulfonyl)imide [BMMI] [TFSI], as the ionic liquid. (C) 2004 Elsevier B.V. All rights reserved.