Stealth is an important factor for an underwater vehicle in littoral operations. A fuel cell hybridized with batteries is a good stealthy power source for air-independent propulsion of the vehicle. This study reported the design, fabrication and testing of a prototype of a small underwater vehicle powered by a proton exchange membrane fuel cell. The fuel cell power system consists of a 1 kW fuel cell stack, hydrogen and oxygen cylinders, lead-acid batteries, a water cooler, solenoid valves, pressure and temperature sensors, and an operational controller. All components are commercially available except for the controller in order to reduce cost. The fuel cell system is installed on a home-made one-man underwater vehicle. The test results demonstrate that the vehicle works,well at maximum 1.05 knots and confirm. the feasibility of the fuel cell system in water. Furthermore, the maximum power of the fuel cell fed by pure oxygen increases 32% than that fed by atmospheric air in the test. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.