Concentration profiles of OH and S 2 in a sulfur-containing premixed H 2 /air flame were obtained and compared to numerical calculations. The measurements utilized degenerate four-wave mixing and absorption spectroscopy in parallel (MULTIPLEX spectroscopy) and were numerically simulated for a one-dimensional flat flame. An established reaction mechanism for hydrogen oxidation was extended by reactions for the sulfur chemistry drawn from the literature. The experimental results for the OH and S 2 concentration profiles are in good qualitative agreement with the simulations. However, the model calculations underestimate the S 2 concentrations by two orders of magnitude, indicating that important intermediates and reactions could have been omitted.