The microwave oven was invented in 1945, when engineer Percy Spencer discovered that microwaves from a radar magnetron could rapidly heat food and then filed the first patent that year.

Quick Scoop: Key Dates

  • 1940: The cavity magnetron tube (core of microwave technology) is invented in England for wartime radar.
  • 1945: Percy Spencer at Raytheon notices a chocolate bar melting in his pocket near an operating magnetron and begins experimenting with heating food, leading to the first microwave oven design and patent filing.
  • October 8, 1945: Raytheon files a patent for a microwave cooking oven based on Spencer’s work.
  • 1947: Raytheon launches the first commercial microwave oven, the “Radarange,” a huge and very expensive unit mainly used in commercial settings.

So when people ask “when was the microwave invented,” the historically accurate answer is 1945, with commercial models appearing a couple of years later in 1947.