This report, prepared within the scope of Subgroup 04 – Marine Fuels Market and in compliance with the National Energy Policy Council (CNPE) Resolution No. 10/2024 dated August 26, 2024—which addresses the Working Group established to support the CNPE in proposing measures and guidelines for the national market of marine fuels, aviation fuels, and liquefied petroleum gas—presents the results of the analysis of the materials and the questions raised. It was communicated during an online presentation held on March 12, 2025. The first part of the document focuses on the composition and pricing models of marine fuels. Price formation is explained based on the accumulated costs along the production chain: approximately 50 per cent resulting from the raw material (oil), 20 per cent to 30 per cent from refining and processing, 10 per cent to 15 per cent from distribution/logistics, and 20 per cent to 40 per cent from taxes—with the latter factor being especially determinant in the cabotage segment. It also highlights the importance of the investments made by refineries to adapt to new requirements, such as those of IMO 2020, which influence both costs and the competitiveness of the national product. The second part of the report addresses the market structure of the sector in Brazil, emphasizing the high concentration at various stages—from refining, dominated by Petrobras, to distribution and retail—which poses challenges for competitiveness, regional variations, and the influence of operational and tax costs on price formation. In comparison with other countries, it is noted that although prices are predominantly defined by the market, there are occasional interventions and significant differences in transparency and regulation, accentuating the need for mechanisms that improve information disclosure. Finally, guidelines and public policies are proposed to stimulate competition and attract investments in the marine fuels market. Among the recommendations, the creation of an integrated and standardized system for the collection and publication of price data, the integration of regulatory agencies information systems, and the revision of tax rules stand out—in addition to investments in the expansion and improvement of port infrastructure, especially in tank storage, which plays a strategic role in the competitiveness of the sector.