An experimental study of flame propagation, acceleration and transition to detonation in hydrogen-airmixture in 2 m long rectangular cross section channel filled with obstacles located at the bottom wallwas performed. The initial conditions of the hydrogen-air mixture were 0.1 MPa and 293 K. Threedifferent cases of obstacle height (blockage ratio 0.25, 0.5 and 0.75) and four cases of obstacle densitywere studied with the channel height equal to 0.08 m. The channel width was 0.11 m in allexperiments. The propagation of flame and pressure waves was monitored by four pressuretransducers and four in house ion probes. The pairs of transducers and probes were placed at variouslocations along the channel in order to get information about the progress of the phenomena along thechannel. To examine the influence of mixture composition on flame propagation and DDT theexperiments were performed for the compositions of 20%2 25%2and 29.6%2of H2 in air by volume. Asa result of the experiments the deflagration and detonation regimes and velocities of flame propagationin the obstructed channel were determined.