Two former college roommates Laurence K. Marshall and Vannevar Bush, along with scientist Charles G. Smith, founded the American Appliance Company in Cambridge, Massachusetts in 1922. The company's first product was a gaseous rectifier, called the Raytheon and used for radio-receiver power supplies that plugged into the power grid in place of large batteries. The company changed its name to Raytheon in 1925.
In World War II Raytheon manufactured magnetron tubes for use in radar sets, and then complete radar systems. (In 1945 Raytheon's Percy Spencer invented the microwave oven by discovering that the magnetron could also cook food.) In 1948 Raytheon began to manufacture guided missiles.semiconductors for the electronics industry. In the late 20th century it produced a wide range of integrated circuits and other components, but as of 2003 its semiconductor business specializes in gallium arsenide components for radio communications.
Civilian lines of business include corporate jet aircraft.