The Fenton reaction was first described by Henry J. Fenton in the late 19th century. It involves the transition of ferrous iron (Fe2+) to ferric iron (Fe3+) through the mediation of hydrogen peroxide, resulting in the formation of hydroxyl radicals (â¢OH). The basic equation is: Fe2+ + H2O2 â Fe3+ + â¢OH + OH- These hydroxyl radicals are among the most reactive species known, capable of attacking a wide range of biological molecules, including DNA, lipids, and proteins.