Overall, this work encompasses an extensive and well-organized literature search. The paper can serve as a guide for a preliminary design of offshore structures for hydrogen production, despite its limited scientific contribution. In my opinion, in fact, it lacks in technical details and does not allow for quantitative comparisons. Throughout the paper, only qualitative comments are provided regarding the literature analysis conducted. Examples are reported below:

• pp10, line 250-253 : Alkaline Electrolysis (AEL) and Proton Exchange Membrane Electrolysis (PEM) have both been reported as preferred solutions in most studies (Bonacina et al., 2022; Henry et al., 2022; Ibrahim et al., 2022; Lucas et al., 2022), with an increasing tendency to the latter due compact design, pressurised operation, load flexibility and fast response, despite being more expensive than the AEL (Buttler and Spliethoff, 2018; D’amore-Domenech et al., 2020).
• pp11, line 272-274 : For the analyses of offshore hydrogen systems, some authors (D’amore-Domenech and Leo, 2019; Meier, 2014) expressed a preference for distillation technology while others (Bonacina et al., 2022; Ibrahim et al., 2022) have preferred reverse osmosis.
• pp11, line 287-289 : The economic feasibility of energy transportation via power cables and gas (compressed hydrogen) pipelines were investigated and concluded that, for long distances, pipeline transmission is cheaper than cables and pipelines have higher energy transmission capacity and lower energy losses.
• pp11, line 290-291 : a pressure of 100 bar is expected to be enough for long-distance hydrogen transportation and suitable for typical existing oil & gas pipelines.

Moreover, the whole section on hydrogen facilities is lacking. Storage and transport, both in centralized and decentralized offshore configurations, electrolyzer technology and desalination systems are just cited, while their impact is crucial in the design of a hydrogen plant. The issues related to storage systems on offshore platforms are superficially addressed, even though dimensions and technical limitations of the technologies are pivoltal in the structure design process. An example is the mere mention of cooling systems for hydrogen liquefaction, which is addressed as the most promising technology in a long-term scenario with no further details:

• pp.11 line 2811-284 : In Babarit et al. (2018) a comparison is made between compressed hydrogen (CH2) and liquefied hydrogen (LH2) concluding that CH2 scenarios have the best energy efficiency, current cost estimates for LH2 and CH2 were similar but LH2 is considered the most promising in the longer term due to expected cost reduction and much greater flexibility for delivery

Additionally, concerning floating platforms, the issue of flexible pipelines is not adequately explored, despite their critical impact for high depths installations.

The paper has a good overall approach assessing the challenges of offshore green (or renewable) hydrogen production. The first two chapters, the overview and key design parameters, present some repetitions and are more focused on offshore wind technology rather than other offshore renewable tecnologies. The combination of hydrogen production with different offshore renewable technologies could present different challenges and opportunity, i.e. hydrogen production system can be integrated in each floating wind turbine, however it is more difficult to imagine a H2 production system integrated in a wave energy converter.  Chapter 4  and 5 are clear and well structured. The paper  is more a litherature review than a critical review because there is the lack of quantitative data to support conclusions.  

1. The paper addresses the relevant scientific question of coupling offshore wind energy (or offshore renewable energy) and hydrogen production, and in particular is focused to the analysis of offshore structure for hydrogen production that are still at the first demonstration stage. 
2. The paper is of broad international interest because offshore renewables are among the more promising technologies worldwide in the future and the coupling with hydrogen production could be a solution for mitigating the variability of the renewable production and could contribute to the development of an sustainable energetic system based on non-electrical vectors.
3. The paper aims to present a critical review, thus there are not novel concepts. The value of the paper is in the final comments even if they are mainly qualitative comments.
4. The method is the literature analysis and thus can be easily reproduced, however, the critical review seems mainly based on the authors’ knowledge and experience and the discussion and the conclusions are more qualitative than quantitative.
5. Assumptions are valid.  They are mainly based on journal articles and pubblications already reviewed.
6. The title is quite long and the term “green hydrogen” is not universally used hydrogen produced by renewables, in example the EU commission prefers the term renewable hydrogen https://www.europarl.europa.eu/RegData/etudes/BRIE/2023/747085/EPRS_BRI(2023)747085_EN.pdf . A suggestion could be “A critical review of challenge and opportunity for designing offshore renewable hydrogen structures”
7. The abstract provides a concise and complete summary, however no quantitative results are reported because of the paper is a review.
8. There is only one figure. If the readers are people from the sector is OK, otherwise some more pictures or rendering could be useful to clarify some concepts, i.e.  the different floating structure type.