A water-soluble ionic conjugated polymer with pyridyl functional groups, poly(2-ethynyl-N-pentylpyridinium iodide) [PEPPI] was synthesized via the activated polymerization of 2-ethynylpyridine using 1-iodopentane without any additional initiator or catalyst. The polymerization proceeded well to provide a high yield of polymer. The polymer structure was characterized by such instrumental methods as NMR ((1)H- and (13)C-), IR, and UV-visible spectroscopies to have a conjugated polymer backbone system having N-pentylpyridinium iodide as substituents. The photoluminescence maximum peak of PEPPI was located at 583 nm, which corresponds to the photon energy of 2.13 eV. The cyclovoltamograms of polymer exhibited the electrochemically stable window at the -1.54 similar to 1.54 V region. It was found that the kinetics of the redox process of PEPPI are mainly controlled by the reactant diffusion process based on the experiment of the oxidation current density of polymer versus the scan rate.