We report on the growth mechanism, structural and optical characterstics of Gallium nitride nanowires prepared on sapphire substrates (0001) by reacting metal gallium with Gallium nitride powder and ammonia in the temperature range of 800 to 1050°C. GaN nanowires samples were characterized by using X-ray diffraction technique which shows wurtzite structure of GaN nanowires and the lattice parameters are calculated. Scanning electron microscopy images reveals that the dimension of the nanowires are around 60 – 80 nm and the length of 1 - 2 millimeters. Three Raman modes of GaN have been observed at frequencies 530, 554 and 564 cm-1. Photoluminescence spectrum reveals the band edge at 3.4 eV and gives yellow luminescence.