Radio frequency reactive sputtering was used to produce gallium nitride films on thermally oxidized silicon substrates at room temperature. Metallic Ga (purity 6N) was used as the target, N 2 and Ar were utilized as sputtering gases. Amorphous GaN was obtained by metal-induced crystallization with a Ni assistance. The nickel particles were scattered onto the surface by rf sputtering and their density was 2 x 10 14 atoms/cm 2 or 4 x 10 14 atoms/cm 2 , which corresponds to 0.02 nm and 0.04 nm thick layer. These values are less than a monolayer thickness, so they are not continuous. Samples were annealed at 700 ºC for 3 h and at 900 ºC for 5 min in a RTP furnace. The 2.5 µm GaN layers grown on the Ni-coated SiO 2 surface recrystalized during annealing forming crystals of (002) orientation. The catalytic regrowth mechanism of GaN is discussed on the basis of experimental results.