When the first countertop microwave oven come out?

The first countertop microwave oven was invented in 1947 by Percy Spencer, a self-taught engineer working for the Raytheon Corporation. Spencer was experimenting with a magnetron, a device used to generate microwaves, when he noticed that a candy bar in his pocket melted. Realizing that microwaves could be used to heat food, he built the first microwave oven, which was about the size of a small refrigerator and weighed 750 pounds. The first commercial countertop microwave oven was introduced by Raytheon in 1954.