On June 25, 1947, Raytheon introduced the Radarange, the first commercially offered microwave oven, to the market. The device grew directly out of radar research during World War II, when engineers discovered that microwaves from magnetrons could heat food quickly. Percy Spencer, an engineer at Raytheon often credited with the immediate discovery of microwave heating in 1945, and his colleagues developed applications for the magnetron that had been refined for wartime radar systems. Raytheon adapted that technology into a large, countertop appliance and began commercial sales in 1947. The original Radarange models were substantial machines compared with modern standards: they were roughly the size of a small refrigerator, weighed several hundred pounds, and were intended primarily for commercial use in restaurants and institutional kitchens rather than private homes. Early units were expensive and required specialized installation and electrical supply, which limited their initial market. Despite these constraints, the ability to heat and defrost food much faster than conventional ovens drew interest from commercial foodservice operations. Early marketing emphasized speed and convenience for businesses, not domestic use. It took further miniaturization, cost reductions, improved safety features, and changing consumer expectations through the 1950s and 1960s before microwave ovens became common in household kitchens. Over time, advances in magnetron design, better shielding and door interlocks, and mass production methods enabled manufacturers to produce safer, smaller, and more affordable models. Historians note that the commercial introduction in 1947 was the start of a longer process rather than an instant cultural revolution. The Radarange represented the first practical transfer of radar-derived microwave technology into food preparation, but widespread domestic adoption unfolded over decades. Sources on this history include company records, contemporaneous trade publications, and later historical studies of kitchen technology and postwar consumer culture. Some aspects—such as the precise timeline of early sales and the detailed roles of individual inventors—are discussed with nuance in historical accounts, and attributions (for example, to Percy Spencer) are often framed within the broader team and corporate context. The 1947 commercial sale of the Radarange stands as a clear milestone: it transformed a laboratory phenomenon into a commercial appliance and set the course for an invention that would reshape cooking practices globally. While the first units were far from the compact household microwaves familiar today, their introduction on June 25, 1947, marks the commercial debut of microwave cooking technology.