William Kemmler (1860/1861 - 1890) of Buffalo, New York was the first person to be executed via electric chair. He had murdered his common-law wife with a hatchet on March 29, 1889, and was sentenced to be executed on August 6, 1890, at 6:00 AM. His lawyers appealed, arguing that electrocution was cruel and unusual punishment; George Westinghouse, one of the backers of AC current, supported his appeal. However, the appeal failed, partly due to the support of Thomas Edison for the state's position (Edison was a backer of the rival DC current, and it is speculated he wanted to use the electric chair's publicity to convince people that AC current was dangerous). See War of Currents

The first attempt at execution failed: Kemmler was electrocuted for 17 seconds, but remained alive. The voltage was increased to 2000 volts, but the generator needed time to charge up again. During this interval, the badly burnt Kemmler could be heard moaning. The second attempt lasted for over a minute and the scene was described by many present as gruesome, with a smell of burning flesh and smoke rising from Kemmler's head.

Westinghouse later commented: "They would have done better using an axe." A reporter who witnessed it also said it was "an awful spectacle, far worse than hanging".