About 20 years ago Fraunhofer ICT has performed large scale experiments with premixed hydrogenair mixtures [1]. A special feature has been the investigation of the combustion of the mixture withina partial confinement, simulating some sort of a ?lane?, which may exist in reality within a hydrogenproduction or storage plant for example. Essentially three different types of tests have beenperformed: combustion of quiescent mixtures, combustion of mixtures with artificially generatedturbulence by means of a fan and combustion of mixtures with high speed flame jet ignition. Theobserved phenomena will be discussed on the basis of measured turbulence levels, flame speeds, andoverpressures. Conditions for DDT concerning critical turbulence levels and flame speeds as well as ascaling rule for DDT related to the detonation cell size of the mixture can be derived from theexperiments for this special test setup. The relevance of the results with respect to safety aspects offuture hydrogen technology is assessed. Combustion phenomena will be highlighted by thepresentation of impressive high speed film videos.