NOVELTY - A miniature electrochemical gas generator comprises electrode of internally located electrochemical cell in intimate contact with a cathode cap and another electrode under compression from an internal spring of variable length that is in electrical contact with the anode cap.    USE - For generating gases or as power source for batteries.    ADVANTAGE - The gas generator is economical, long-life, and disposable. It can also be controllably operated for long time periods and does not require unusual skills, tools, or equipment. Only minor modifications of the generators are required to achieve the desired longevity. The low-cost device is easy to fill and assemble. It can be used for the controlled release of small quantities of fluid, delivered at low flow rates for long periods of time, e.g. fragrances, insecticides, or pesticides.    DETAILED DESCRIPTION - A miniature electrochemical gas generator comprises an elongated plastic tube having non-electrical conducting properties and top and bottom ends, an interior chamber, an outer diameter D1 (less than 25 mm), an inner diameter D2, and a length L1 (less than 50 mm). A top end cap (2A) has a first tubular sleeve closed by a top end wall and having an inner surface and an inner diameter D3. It is made of metal and has electrical conducting. The end cap functions as a current collector. A gas release port (8) is formed in the top end wall for releasing gases. A bottom end cap (2B) has a second tubular sleeve closed by a bottom end wall and having an inner diameter D3. It is made of metal and has electrical conducting properties. The bottom cap functions as a current collector. An electrochemical cell (4) module has two electrodes and is positioned within the bottom end cap with the first electrode in electrical contact with the bottom end cap. A gas permeable membrane (7) has a bottom surface and an outer diameter equal to D3 that seals the gas permeable membrane against the inner surface of the first sleeve. It is positioned in the top end cap adjacent to the top end wall. A metallic retaining ring (5) having a central aperture, top and bottom surfaces, and an outer diameter equal to D3 is positioned in the top end cap adjacent to the membrane. It is in electrical contact with the top end cap. An elongated metal wire or spring (3) is positioned within the plastic tube with top end in electrical contact with top end cap and bottom end in electrical contact with the second electrode. An amount of carboxylic acid solution is in the interior chamber of the plastic tube. The carboxylic acid is formic acid or oxalic acid. Methanol can be in the tube. A metal hydride, preferably sodium borohydride is in the interior chamber of the tube. An INDEPENDENT CLAIM is included for a miniature fuel cell.    DESCRIPTION OF DRAWING(S) - The figure is a schematic exploded front perspective view of electrochemical gas generator.    Top end cap (2A)    Bottom end cap (2B)    Spring (3)    Electrochemical cell (4)    Metallic retaining ring (5)    Gas permeable membrane (7)    Gas release port (8)