The subject of the project is the detailed investigation of mixture formation in hydrogen combustion engines. Mixture formation and homogenization is crucial for efficient engine operation and minimization of nitrogen oxide emissions. The predominant mixture formation strategies, port fuel injection and direct injection, are investigated. The complexity of the experimentally and numerically investigated configurations will be gradually increased, from hydrogen injection into a quasi-quiescent atmosphere, to generic flow bench experiments under engine-like conditions, to an optically accessible single-cylinder engine. The experimental data will be used to validate Large Eddy simulations (LES) created in parallel. The multi-cycle LES will describe the transient flow and support the analysis of the mixing processes. Finally, selected concepts are integrated into IC engine test beds and evaluated in terms of their effective influence on combustion.