Thomas Hurley III gave the correct answer to the Final Jeopardy question about the Emancipation Proclamation signed by President Abraham Lincoln. However, Hurley spelled it "emanciptation" and was ruled out by host Alex Trebek.
Hurley bet $3,000 of his $9,600 in winnings and finished well behind a rival who amassed $66,600.
"I was pretty upset that I was cheated out of the final 'Jeopardy!' question," he told The News-Times of Danbury. "It was just a spelling error."
The middle school student from Newtown, Conn. won $2,000 as the runner-up.
The show defended Trebek's decision in an email.
"If 'Jeopardy!' were to give credit for an incorrect response (however minor), the show would effectively penalize the other players," they said. "We love presenting young people as contestants on our show and make every effort to be fair and consistent in their treatment."
The boy's mother, Suzanne, said her son was "a little stunned" by the loss and embarrassed.
"It was hard to watch," she described.
Hundreds vented their anger at "Jeopardy!" and Trebek on the game show's Facebook page.
"Bad form, Jeopardy," said one comment. "Every game show has bad calls ... this takes the cake."
The "Kids Jeopardy!" program was filmed in February and broadcast last week.
The Associated Press contributed to this report.