The impingement of a jet on a flat surface is a flow configuration of interest in many engineering applications. Of particular interest in this study, it is a generic flow encountered in assessments of the consequences of releases of flammable material on process plant. Experimental data, obtained using laser Doppler anemometry, are presented for the turbulent velocity field in the radial wall jet formed by a high momentum release of methane impinging normally on a flat surface. Mean and fluctuating concentration data obtained using laser Raman spectroscopy are also described, and compared with mean data gathered using aspirated hot film probes. Velocity results are generally in good agreement with data on impinging air jets obtained using particle image velocimetry techniques, although significant differences do occur with earlier hot-wire anemometer measurements. Measured concentrations are in similar agreement with earlier data on impinging air jets obtained using a Mie scattering technique, although differences again occur between mean concentrations obtained using both laser-based techniques and aspirating probes. The provision of a single data set that contains information on both the velocity and conserved scalar fields is of value for improving understanding and in permitting the formulation and validation of RANS models of impinging flows. (C) 2004 Elsevier Ltd. All rights reserved.