The characterization of a main-chain metallomesogenic polyester has been carried out by differential scanning calorimetry, dielectric relaxation spectroscopy and dynamic mechanical analysis. The mesogenic repeat unit of the polyester derived from a salicylaldimine copper(II) complex shows a nematic phase like conventional organic liquid-crystal polymers. This semicrystalline polymer displays a set of different relaxation processes, such as beta relaxation, alpha relaxation, melting process, cold crystallization effects and conductivity contributions, which have been carefully studied.