Korea has introduced one of the world’s first legally mandated Clean Hydrogen Certification Schemes as part of its national strategy to achieve carbon neutrality by 2050. However, certification outcomes are highly sensitive to methodological choices, making assurance of credibility and fairness a critical challenge. To strengthen robustness, this study compared international life cycle assessment (LCA) guidelines and standards to identify elements applicable for institutional adoption. Thirteen policy-oriented hydrogen LCA studies were reviewed to derive design factors for improving Korea’s scheme. Five core factors of functional units, system boundaries, co-product definition, allocation procedures, and data quality were identified, along with three additional factors of cut-off criteria, GWP (Global Warming Potential), and electricity procurement rules. Analysis of international guidelines revealed uncertainties and barriers to comparability in the Korean scheme. Suggested improvements include specifying pressure conditions in functional unit definitions, predefining co-product lists, stipulating allocation methods differentiated by co-product categories, and establishing data quality criteria for items lacking default values. The additional factors also require refinement. For cut-off rules, clear thresholds and application criteria should be codified. Regarding electricity procurement, ensuring low-carbon integrity requires more granular reporting intervals and explicit rules for calculating emissions from power supplied through energy storage systems. In conclusion, while Korea’s Clean Hydrogen Certification Scheme provides a pioneering framework, refinements are essential to ensure consistency, reproducibility, and international alignment. By systematically identifying uncertainties and proposing improvements, this study contributes to enhancing the credibility and fairness of institutional LCAs for clean hydrogen certification.