Thermal polymerization of bis(pyridine)bis(trichlorophenoxo)copper(II) was achieved in the solid state for the first time. The time and temperature effect on polymer molecular weight, percentage yield and the structure of polymer was first studied, at constant temperature and then for constant decomposition time. Polymers were characterized by i.r., H-1 n.m.r. and C-13 n.m.r. The molecular weights of the polymers were obtained by viscometric measurements at 30-degrees-C in toluene and glass transition temperatures were obtained by d.s.c.