A critical damage pattern in underwater welding processes is the formation of hydrogen-induced cold cracks, which do not occur immediately after welding. The electrolytic dissociation of the water during arc welding creates a large supply of hydrogen. As an alternative, laser beam welding could be used in the underwater industry in the future. A low hydrogen concentration is expected due to thermal dissociation only. In this paper, laser beam welds are performed with Yb:YAG-laser on 10 mm S235JR-steel and the diffusible hydrogen content of this samples is determined using carrier gas hot extraction. The laser beam power is varied between 3 kW and 4 kW and the feed rate between 0.25 m/min and 0.50 m/min to analyse their influence on the hydrogen content. In addition, the process zone is analysed about hydrogen formation using a high-speed camera and spectrometer. The results are compared with the hydrogen content of shielded metal arc-welded samples