The high efficiency and scalability of fuel cell systems make them attractive for a range of Naval applications that span sensors and unmanned systems to microgrids and ships. Anticipated benefits include significant endurance enhancements that extend range and on-station mission capability and reduced use of fossil fuels to increase energy independence and energy security. Prior Navy and other agency investments in fuel cell stack technology, reactant storage and processing systems, and balance of plant components has enabled the design, fabrication and integration of practical fuel cell systems. These systems have demonstrated superior performance to other technologies and the ability to fill capability gaps that other technologies are unable to address. This paper will discuss the status of fuel cell systems for Naval applications and the challenges and opportunities for Fleet and Marine Corps implementation.