Most of the jet penetration studies in gas-solid fluidized beds are for subsonic gas jets, for which many correlations can be found in the literature. In this work, horizontal supersonic gas jets, produced by convergent-divergent nozzles, have been studied, and the intent was to investigate the relationship between the thrust produced by supersonic nozzles and the jet penetration. Different nozzle geometries were used, with three gases having different characteristics (air, helium and carbon dioxide) and at different pressures. All the experimental runs were performed with silica sand particles with the same particle size distribution, and the fluidization velocity was set at a constant value of 0.09 m/s. Jet penetration was measured with a set of triboelectric probes, and it was found that the correlation proposed by Merry, although originally developed for subsonic gas jets, fits really well the experimental results. It was also confirmed that jet penetration displays a strong correlation with the thrust produced by the convergent-divergent nozzles. A correlation originally proposed by Benjelloun's has been modified and the corrected correlation gives the best predictions for gas jet penetration (c) 2011 Elsevier B.V. All rights reserved.