Xtol is a photographic developer manufactured by Eastman Kodak company.
Xtol is one of the few developers that do not contain hydroquinone. It uses derivatives of ascorbic acid (vitamin C) and phenidone as developing agents. Claimed advantages include low toxicity (important for environmental reasons as well as occupational safety), easy mixing, and an unusual combination of fine grain with high film speed.
Xtol is covered by a US Patent and sold in a powdered form to make 5 liters of developer.
References
Xtol Wikipedia(Text) CC BY-SA