This paper presents results from laboratory experiments with hydrogen dispersions and explosions in a 3 m long channel. Our objective is to get a better understanding of the phenomena and to develop tools that can analyse hydrogen dispersions and explosions. A total of 5 test series were performed with flow rates of hydrogen from 1.8 dm(sup 3)/min to 75 dm(sup 3)/min. The propagation of the combustible hydrogen-air cloud in the channel was observed from high-speed video recordings. The hydrogen-air cloud in the channel behaves as a gravity current and the flow appears to be well described by Froude scaling with a length scale corresponding to the height of a layer of 100%2hydrogen. The Froude numbers observed in the experiments are in good agreement with the theory of "light-fluid intrusion" for gravity currents found in the literature. Numerical simulations with the Flacs code correlate well with the experimental results. The flame propagation indicated that approximately half the height of the channel was filled with combustible mixture. We believe that this Froude scaling can be useful as a tool to analyse the consequences of hydrogen release in buildings, channels and tunnels.