A new polyacetylene based polyelectrolyte, poly(N-3,4-dimethoxybenzoyl-2-ethynylpyridinium chloride), was synthesized by the direct polymerization of 2-ethynylpyridine and 3,4-dimethoxybenzoyl chloride. The polymerization successfully proceeded without any additional catalyst or initiator to give a high yield of the product. The chemical structure of poly(N-3,4-dimethoxybenzoyl-2-ethynylpyridinium chloride) was confirmed using H-1 and C-13 nuclear magnetic resonance spectroscopy, as well as Fourier transform infrared spectroscopy. Further, optical properties, electrochemical properties, and thermal stabilities were investigated by cyclic voltammetry, UV-Vis absorption spectra, photoluminescence spectra, thermogravimetric analysis. Comparing UV-Visible absorption and photoluminescence spectrum, the polymer showed the band gap of 2.18 eV and photon energy of 2.58 eV.