This standard provides technical requirements and guidance for the certification of electrolyser systems. It defines relevant hazard evaluation and safety studies required to assess electrolyser systems and the risks associated with hydrogen production. It establishes system- and component-level requirements to be met, with the intention of ensuring safe operation during the life of the electrolyser. Requirements addressing all phases of the electrolyser system, including design, manufacturing, installation, commissioning, and operation, are provided. This standard uses the approval and certification process described in DNV-SE-0674.