The inherent advantages of quiet operation, few moving parts, and compact and lightweight construction make thermoelectric generators desirable for specialized military uses. Recent developments in the thermoelectric couple and thermopile enclosure fabrication have shown promise for successful generator sizes that can meet present military needs for portable power up to 3 kw.Design, development, and test of two 300 w portable thermoelectric generators by the U. S. Navy Marine Engineering Laboratory are described. The generator weighs only 35 lb, including diesel, kerosene, or jet fuel for 8 hr of operation. The cooling fan operating from power produced by the thermoelectric couples is the only moving part. The Laboratory is investigating minor modifications needed for units to be used by the Marine Corps in field trails.The performance characteristics of the new 300 w thermoelectric generators and other power sources presently available are compared.