Gallium oxide (β-Ga 2 O 3 ) nanoparticles were successfully deposited on quartz glass substrates using sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/n-hexane/ethylene glycol monomethyl ether (EGME) reverse micelle-mediated solvothermal process with different w values. The mean diameter of Ga 2 O 3 particles was ∼2–3 nm and found to be approximately independent of w values of the reverse micelles. However, when the Ga 2 O 3 nanocrystalline films were nitrided at 900 °C under flowing NH 3 atmosphere for 1 h, the mean diameter of the resulted gallium nitride (wurtzite-GaN) nanoparticles varied from 3–9 nm. Both nanocrystalline films of Ga 2 O 3 and GaN were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, UV–vis spectroscopy and photoluminescence in order to study their chemical and physical properties explicitly.