Novel mono-substituted polyacetylenes bearing urea groups in side chains, i.e. poly(N-propargylureas), were successfully synthesized for the first time. The solubility of the resulting three polymers (poly(1)-poly(3)) was examined, and it was found that the solubility of them largely depended on the pendent groups; the polymer with benzene cycle (poly(2)) showed high solubility in polar solvents including DMF and DMSO. The effects of polymerization temperature, solvents, and the ratio of monomer concentration to the catalyst concentration ((nbd)Rh+B-(C6H5)(4) (nbd = norbornadiene)) on the polymerization of monomer 2 were investigated. Poly(2) could be obtained with moderate molecular weights (20,100-29,200) in high yields (>= 90%), and the cis content of the polymer backbones was quite high (>= 96%). (c) 2006 Elsevier Ltd. All rights reserved.