A gas engine is an internal combustion engine that runs on a fuel gas, such as coal gas, producer gas, biogas, landfill gas, natural gas or hydrogen. In the United Kingdom and British English-speaking countries, the term is unambiguous. In the United States, due to the widespread use of "gas" as an abbreviation for gasoline (petrol), such an engine is sometimes called by a clarifying term, such as gaseous-fueled engine or natural gas engine.

INNIO Jenbacher designs and manufactures gas engines and cogeneration modules in the Austrian town of Jenbach in Tyrol. It is part of the INNIO portfolio of products and is one of their gas engine technologies; the other being Waukesha Engines. Jenbacher emerged from the former Jenbacher Werke, which was founded in 1959 and manufactured gas and diesel engines, and locomotives. The company was bought out by General Electric in 2003. In November 2018 the company became part of INNIO as part of an acquisition of Advent International and was renamed INNIO Jenbacher GmbH & Co. OHG.