A turbogenerator is an electrical generator connected to the shaft of a steam turbine or gas turbine for the generation of electrical power.[1]​ Large steam turbogenerators provide most of the world's electricity and are also used by turboelectric steam ships.[2]​.

Small turbogenerators driven by gas turbines are often used as auxiliary power units (APUs, mainly for aircraft).

The first turbogenerators were electrical generators driven by hydraulic turbines. The first Hungarian hydraulic turbine was designed by the engineers of the Ganz Works "Ganz (company)") in 1866; Industrial-scale production with dynamo generators began only in 1883. Engineer Charles Algernon Parsons demonstrated a DC steam turbogenerator using a dynamo "Dynamo (Electric Generator)" in 1887, and by 1901 he had developed the first large industrial AC turbogenerator with power on the order of megawatts for a plant in Eberfeld, Germany.

Turbogenerators were also used in steam locomotives as a power source for carriage lighting and water pumps for heating systems.

Turbogenerators are used for high shaft rotation speeds, typical of steam and gas turbines. The rotor "Rotor (electrical machine)") of a turbogenerator is a type of non-salient pole, "Rotor (electrical machine)") generally with two poles.[6]​.

The normal speed of a turbogenerator is 1500 or 3000 rpm with four or two poles at 50 Hz (1800 or 3600 rpm with four or two poles at 60 Hz). The rotating parts of a turbogenerator are subject to high mechanical stress due to the high operating speed. To make the rotor mechanically strong in large turbochargers, the rotor is usually forged from solid steel and alloys such as chromium-nickel-steel or chromium-nickel-molybdenum are used. The overhang of the windings at the periphery shall be secured by steel retaining rings. Heavy non-magnetic metal wedges at the top of the slots hold the field windings against centrifugal forces. Hard composition insulating materials, such as mica and asbestos, are typically used in the rotor slots. These materials can withstand high temperatures and high crushing forces.[7]​.

The stator of large turbogenerators can be constructed in two or more parts, while in smaller turbogenerators it is constructed in one complete piece.[8]​.