A spontaneous Raman scattering apparatus based on a flashlamp-pumped dye laser has been developed for single-pulse temperature and concentration measurements of very high accuracy. Comprehensive data sets from measurements in two turbulent H-2/N-2/air jet diffusion flames are presented comprising mean values and fluctuations of the temperature and major species concentrations. Differences in the behaviour of an attached and lifted flame, operated under identical flow conditions and fuel composition, are shown. The effect of differential diffusion and its dependence on flow velocity are investigated in detail. One of the main aims of this work is the establishment of data sets which are suitable for testing mathematical dame models. As an example, the experimental results from one flame are compared to theoretical predictions from a Reynolds-Stress model.