Titanium dioxide, micelles on glass substrate were generated in situ in a water-in-oil (w/o) microemulsion composed of water, dioctyl sulfosuccinate sodium salt (AOT), and cyclohexane, by controlled hydrolysis of TiCl4. The average grain size [R], obtained by grazing-incidence small-angle X-ray scattering (GISAXS), was 6.3 +/- 0.8 nm. "Corrected specific surface" of TiO2 micelles was determined as 5.0 x 10(5) cm(-1). The average grain size [R] of 5.0 +/- 1.3 nm obtained by grazing-incidence wide-angle X-ray scattering (GIWAXS) agrees with GISAXS value. GIWAXS can detect smaller amounts of additional phases or impurities than classical X-ray diffraction equipment.