Eighty years ago today, on October 8, 1945, the Raytheon Manufacturing Company filed a patent for an invention that would forever change the way we cook: the microwave oven.
The story begins with Percy Spencer, an electrical engineer at Raytheon with an extraordinary self-made background. Twice orphaned as a child, Spencer never finished grammar school. Working factory jobs as a boy, he studied late into the night—teaching himself calculus, trigonometry, physics, and chemistry by lamplight. At 18, he joined the U.S. Navy to gain experience with wireless communications, where he became an expert in radio technology.
By 1939, Spencer had risen to become one of the world’s foremost authorities on radar tube design and was appointed chief of Raytheon’s power tube division. There, he worked on equipment used in radar systems—specifically magnetrons, which emit microwaves.
According to legend, one day while working near an active radar set, Spencer noticed a candy bar in his pocket had melted. Curious, he began experimenting. The first food he intentionally cooked using microwaves was popcorn. The second—an egg—exploded in a colleague’s face. Despite the mishap, the breakthrough was clear: microwaves could cook food quickly and efficiently.
On October 8, 1945, Raytheon filed a U.S. patent for Spencer’s microwave cooking process. Spencer didn’t receive royalties for his invention, but he did get a token $2 payment—the standard company policy for employee patents at the time.
In 1947, Raytheon introduced the Radarange, the first commercial microwave oven. It stood nearly six feet tall, weighed 750 pounds, cost around $5,000 (about $70,000 today), and required water cooling. Unsurprisingly, it didn’t find its way into many homes. Concerns about microwave radiation, combined with its size and price, kept the technology largely confined to restaurants and industrial use.
That changed in 1967, when Amana, a Raytheon subsidiary, released the first countertop microwave. At $495 (roughly $4,600 today), it was still pricey, but it marked the beginning of the microwave’s journey into the American home. New features soon followed—automatic defrost in 1974, and digital controls in 1975. By 1986, one in four U.S. households owned a microwave; today, that number is over 90%.
The 1980s also saw another revolution: microwave popcorn. Minnesota’s Golden Valley introduced the first microwave popcorn in 1981 under the name Act I, which needed refrigeration. A few years later, the company launched Act II—the first shelf-stable version and a runaway hit. By the mid-1990s, microwave popcorn made up 65% of all popcorn sales.
Even with all the modern upgrades—sensors, presets, and sleek touchscreens—the microwave’s role hasn’t changed much. According to a Lawrence Berkeley National Laboratory study, 68% of people use their microwaves for three minutes or less at a time, with most “nuking” their food between one and two minutes.
From a melted candy bar to a must-have appliance, the microwave oven’s story is a perfect mix of curiosity, ingenuity, and everyday convenience—80 years and counting.