– Nitric Oxide (NO) is a free radical gas that is involved in a variety of biological processes including regulation vascular tone, neuronal signaling, and host defense. Nitroxyl (HNO) is the one electron reduced form of nitric oxide. Piloty’s acid is one of the best known and most widely used HNO donors. Under basic conditions Piloty’s acid decomposes to HNO and benzenesulfinate anion. The rate of HNO release at pH 7 is very slow (t = 5,500 minutes) making its use most effective above pH 8.0. The half-life of Piloty’s acid decreases with an increase in pH to 561, 90, and 33 minutes at pH 8.0, 9.0, and 10.0, respectively. Piloty’s acid also inhibits yeast aldehyde dehydrogenase with an IC50 or 48 μM.