Intrinsically soluble copolymer with well-defined alternating substituted 2.5 p-phenylenevinylene (2.5 PV) and hexanedioxy blocks was synthesized by using the Wittig reaction. The copolymer was characterized with FTIR, H-1 NMR, UV-vis and fluorescence techniques. Thermal properties were investigated with DSC and TGA under nitrogen atmosphere. Time-resolved studies done on the polymer solution and film indicate that the polymer has a re combination time in the region of 20 mu s, which is four order of magnitude greater than that reported for the PPV. A single-layer light-emitting diode device having a simple ITO/polymer/Al configuration was fabricated. The forward bias current was obtained and the device shows typical diode behaviour. Photodegradation of the copolymer was also studied by applying high-intensity UV illumination as well as low-intensity irradiation at a fix wavelength to the polymer film.