Hydroxylates phenol to catechol (PubMed:1429434, PubMed:4146224, PubMed:3203745, PubMed:2022646, PubMed:7858421, PubMed:7851397, PubMed:11591156). Phenol is the best substrate, but the enzyme also accepts isomeric diphenols, hydroxyl-, amino-, halogen- or methyl-substituted phenols and, to a lesser degree, cresols (PubMed:4146224, PubMed:17425111, PubMed:7851397). H(+) + NADPH + O2 + phenol = catechol + H2O + NADP(+) Inhibited by excess phenol (PubMed:4146224). Heavy metals such AsCuSO(4), AgNO(3), or HgCl(2) severely inhibit activity (PubMed:4146224). Optimum pH is 7.2-7.6. Optimum temperature is 30 degrees Celsius. Aromatic compound metabolism; phenol degradation. Homodimer. Belongs to the PheA/TfdB FAD monooxygenase family.