Phenidone (1-phenyl-3-pyrazolidinone) is an organic compound that is primarily used as a photographic developer. It has ten to eighteen times the amount of efficiency and stability as Metol, capable of achieving the same level of development in both less time and at a lower concentration. It also has low toxicity and unlike some other developers, does not cause dermatitis upon skin contact. As a developer, Phenidone is typically used in conjunction with hydroquinone for black and white photography and performs better at lower pH levels. This is comparable to Metol whose working pH is approximately 10.3.