This paper presents results from laboratory experiments with hydrogen dispersions and explosions in a3 m long channel. Our objective is to get a better understanding of the phenomena and to develop toolsthat can analyse hydrogen dispersions and explosions. A total of 5 test series were performed withflow rates of hydrogen from 1.8 dm?/min to 75 dm?/min. The propagation of the combustiblehydrogen-air cloud in the channel was observed from high-speed video recordings. The hydrogen-aircloud in the channel behaves as a gravity current and the flow appears to be well described by Froudescaling with a length scale corresponding to the height of a layer of 100 %2hydrogen. The Froudenumbers 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 wellwith the experimental results. The flame propagation indicated that approximately half the height ofthe channel was filled with combustible mixture. We believe that this Froude scaling can be useful as atool to analyse the consequences of hydrogen release in buildings, channels and tunnels.