Flowers For Algernon author Daniel Keyes has died, aged 86.

Keyes passed away at his home in Florida on Sunday (15Jun14) after suffering complications from pneumonia, his daughter Leslie Keyes told The New York Times.

The author is best known for Flowers for Algernon, a story about a man with a low Iq who becomes a genius after an operation. It was first released as a short story in 1959 before being expanded into a novel in 1966.

The story was adapted into the 1968 movie Charly, which earned Cliff Robertson a Best Actor Oscar for his portrayal of the title character.

Keyes wrote four more novels and three non-fiction books, including The Minds of Billy Milligan, as well as releasing a memoir in 1999 to celebrate the 40th anniversary of his most famous work.