To obtain a copolymer of an acetylenically unsaturated compound which has an improved conductivity.

A copolymer is obtained by copolymerizing an acetylenically unsaturated compound and optionally an olefinically unsaturated compound with carbon monoxide, wherein monomers are preferably contacted with a catalyst composition based on: (a) a source of palladium, and (b) an anionic phosphorous ligand of the general formula: R1R2P-R3-X (wherein R1 and R2 independently represent each optionally a polar substituted hydrocarbyl group, R3 is a bivalent bridging group having 2 carbon atoms in the bridge and X is an anionic group).