The decarbonization of the maritime sector represents a priority in the energy policy agendas of the majority of Countries worldwide, and the International Maritime Organization (IMO) has recently revised its strategy aiming for an ambitious zero-emissions scenario by 2050. In these regards, there is a broad consensus on hydrogen as one of the most promising clean energy vectors for maritime transport, and a key towards that goal. However, to date, an international regulatory framework for the use of hydrogen on-board of ships is absent, this posing a severe limitation to the adoption of hydrogen technologies in this sector. To cope with this issue, this paper presents a preliminary gap assessment analysis for the International Code of Safety for Ship Using Gases or other Low-flashpoint Fuels (IGF Code) with relation to hydrogen as a fuel. The analysis is structured according to the IGF Code chapters, and a bottom-up approach is followed to review the code content and assess its relevance to hydrogen. The risks related to hydrogen are accounted for in assessing the gaps and providing a first level set of recommendations for IGF Code updates. By this means, this work settles the basis for further research over the identified gaps, towards the identification of a final set of recommendations for the IGF Code update.