Field experiments of a high pressure release of hydrogen gas inside a 6 m long, 0.9 m wide, and 0.8 m high channel have been performed, to validate the Froude scaling and to obtain pressure and flame speed data in an inhomogeneous hydrogen-air cloud. Froude scaling with a length scale corresponding to the height of a 100% hydrogen layer in the channel was used to describe the flow of the hydrogen-air cloud in the channel. The estimated time of ignition based on the Froude scaling for release pressures of 100 bars and 150 bars agreed well with the experiments. At lower release pressures the estimated time was lower, which was most likely caused by dilution of the front of the hydrogen cloud. High speed video was used to record the flame speed. For the present experimental conditions it appeared that the deflagration taking place closer to the jet source determines the maximum explosion pressure. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.