We developed a new series of single-component air- and moisture-stable catalysts for alkyne polymerization based on nickelocene complexes containing phosphine and alkynyl ligands. Chlorine. phosphine and alkynyl ligands exhibited great influence on the catalytic activity of the nickelocene complexes. Highly soluble polymers with fairly high molecular weight ((M) over bar (w) 23 400) were obtained in high yields (85%) in the homogeneous polymerization of p-diethynylbenzene initiated with five nickelocene acetylides (pi -C5H5)LNi(C=CR) (L = PPh3, PBu3; R = p-C6H4C=CH, C6H5, H) under mild conditions.