Abstract Optical emission spectra of rich HMDSO/propane/air and propane/air flames (equivalence ratio Φ=1.33) were recorded using an imaging spectrometer in combination with an intensified CCD camera. The probe area was about 1×0.2 mm2. This is small for the OES signal and allows scans of high spectral and spatial resolution across the flame. Emission lines of Si⁎ (∼252 nm) and SiO⁎ (220–265 nm) were registered at different heights above the slit burner. Si⁎ and SiO⁎ were found up to 10 and 40 mm above the burner, respectively. Up to a HMDSO concentration of 0.015% in the total gas flow a linear dependence between Si⁎ and HMDSO concentration could be proved. Gas temperatures were determined using Raman scattering by N2 molecules and compared with temperatures derived from simulations of CH⁎ (A–X) and OH⁎ (A–X) spectra. N2 and CH⁎ temperatures are within (1950±50) K and (2400±500) K in a good agreement, respectively. At a height of 12 mm above the burner the OH⁎ (A–X) molecules have a temperature of (6700±500) K. We suggest to position substrates for coating applications in a distance of 8 to 10 mm from the burner to use the high OH⁎ concentration for SiO2 layer deposition.