Catalytic oxidation in the aqueous phase of phenol and phenol-derivates present in pharmaceutical wastewaters has been investigated using FeSO4 center dot 7H(2)O as a homogeneous catalyst at 413 K and 1 0 MPa Different initial pH values and catalyst concentrations have been tested, and the results obtained have been discussed taking Into account the different roles that the iron plays depending on the pH value and the phenolic compound studied The degradation rate of each pollutant assayed and the degree of mineralization achieved during the wet oxidation process were greatly affected by pH The catalytic effect of iron(II) during the wet oxidation of phenol was only observed at pH values ranging between 2 and 3, due to the establishment of a Fe(III)/Fe(II) redox cycle However, the best results for the catalytic oxidation of salicylic acid were obtained for pH values below 2, and they were related to the formation of an Fe(II)-salicylic acid complex On the other hand, the presence of iron(II) had a prejudicial effect on the degradation of p-hydroxybenzoic and 5-hydroxyisophthalic acids, provoking the apparition of induction periods in both cases, due to the competition between the autoxidation of Fe(II) and the hydroxylation of the phenolic compound by the initial OH