Metoprolol degradation by FeIII-NTA/H2O2 was enhanced in the presence of MnII. Rapid degradation of metoprolol was obtained by FeIII-NTA/H2O2-Mn at pH 4.0–8.0. FeIII-NTA/H2O2-Mn led to more efficient degradation of metoprolol and intermediates. Degradation pathways of metoprolol were proposed.