Linear, crankless, internal combustion engines may find application in the generation of electrical power without the need to convert linear to rotary motion. The elimination of the connecting rod and crankshaft can improve the efficiency of the engine significantly and the reduced weight and cost are added advantages. A linear, crankless, internal combustion engine prototype has been developed for electrical power generation in combination with a linear alternator. The operation of this engine is distinct from that of a conventional slider-crank mechanism engine, insofar as the motion of the two horizontally opposed pistons is not externally constrained. A two-stroke engine prototype, with a bore of 36.5 mm and a maximum stroke of 50 mm, operating in a gasoline-fueled spark-ignited mode, was tested successfully under varying externally-applied load and ignition timing conditions. An idealized model analysis also provided an insight into the behavior of the linear engine for different stroke-to-bore (L/b) ratios and under different air-to-find ratios. (Abstract shortened by UMI.)