FIELD: chemical industry. SUBSTANCE: described is method of isomerization of 2-methylbutene-3-nitrile into linear pencenenitrile in the presence of catalyst based on nickel compound and phosphine compound. Reaction is carried out in aqueous solution of catalyst comprising sulfonated phosphine of general formula I 
: Ar1,Ar2 and Ar3 wherein Y1,Y2 and Y3 ar phenyl; NO2 are the same or different and are alkyl containing 1-4 carbon atoms, alkoxy containing 1-4 carbon atoms, halogen atom, (N, NR1R2, OH or R1 and R2 wherein N/R3R4R5R6/+ are the same or different and are alkyl having 1-4 carbon atoms; M is mineral or organic cation selected so that compound of formula I is soluble in water from group consisting of H, alkali or alkali-earth metal cation; R3R4R5 and R6, wherein m1,m2 and m3 are the same or different and are alkyl having 1-4 carbon atoms, or hydrogen atom; n1,n2 and n3 are integers, the same or different and are from 0 to 3, one of said integers being equal or greater than 1, and a nickel compound. EFFECT: reduced content of by-product. 13 cl, 12 ex, 5 tbl
