NOVELTY - The apparatus (10) has a flexible plenum enclosed by flexible walls, where one of the flexible walls includes a first flexible two-dimensional fuel cell array including fuel cells with anodes accessible from a first side of the first flexible array and cathodes accessible from a second side of the first array. One of the first side or the second side is accessible within the plenum, where one of the flexible walls expands outward. A fuel inlet connects the plenum to a source of pressurized reactant e.g. fuel. An external support structure (25) limits outward expansion of the walls.    USE - Electrochemical fuel cell apparatus for supplying electrical power to vehicles e.g. automobiles and aircrafts, and portable electronic device i.e. personal digital assistants. Can also be used for personal computing devices e.g. tablet/laptop computers and personal computers, entertainment devices e.g. TVs, music players, video players, cameras, video cameras and sound recorders radios such as two-way radios, communication devices e.g., cellular telephones and satellite telephones, safety devices e.g. personal alarms, flashlights, beacons and warning lights, technical equipment e.g. electronic testers, oscilloscopes and frequency generators, and small appliances e.g. portable vacuums and portable dust blowers.    ADVANTAGE - The fuel cells are arranged to conform to a housing of the device in a relatively thin layer, thus minimizing intrusion of the fuel cells within the envelope of the device being powered, and hence permitting portable electrically-powered devices to be made more compact and permitting volume within the housing of a portable electronic device in a reliable and flexible manner. The apparatus reduces weight of an array of fuel cells by making the sheet thin, thus improving efficiency of fuel cells by making the sheet thin in a cost effective manner.    DESCRIPTION OF DRAWING(S) - The drawing shows a perspective view of a fuel cell apparatus.    Fuel cell apparatus (10)    Fuel cell component (12)    Port (20)    External support structure (25)