Who invented the microwave oven and received U.S. patent 2,495,429?

Percy Spencer invented the microwave oven and received U.S. patent 2,495,429 for a microwave food-treatment method.

Spencer was an American engineer working for Raytheon on magnetrons, the vacuum tubes that generated microwave energy for radar systems. In 1945, he noticed that radiation from an operating magnetron had melted a candy bar in his pocket. He tested the effect with other foods, including popcorn, and helped demonstrate that concentrated microwaves could heat food rapidly.

His patent, filed in 1945 and granted on January 24, 1950, described directing microwave energy into a confined area and moving food through it, rather than describing the compact countertop ovens found in modern kitchens. Raytheon developed the first commercial microwave oven from this work; the early Radarange was large, expensive, and intended mainly for institutional use.

The answer is sometimes complicated by the involvement of Raytheon. Raytheon was Spencer’s employer and the company that developed and commercialized the technology, but Percy Spencer was the inventor named on patent 2,495,429. Charles Kettering and James West are associated with other inventions, not this microwave breakthrough.