Antibiotics are currently recognized as environmental pollutants. In this work, the methods involved in the degradation of a β-lactam antibiotic (i.e., DXC) by treatments based on inorganic peroxides and UVC (e.g., UVC alone, UV-C/H2O2, UVC/peroxymonosulfate, and UVC/peroxydisulfate) are presented. The methodology of computational calculations to obtain frontier orbitals and Fukui indices for DXC, and elucidate the reactive moieties on the target substance is also shown. Finally, the direct oxidation by peroxides and UV-C/H2O2 action to treat DXC in simulated pharmaceutical wastewater are depicted. The chromatographic and theoretical analyses allowed for determining the degrading performance of inorganic peroxides and UVC-based treatments toward the target pollutant in aqueous samples.•Treatments based on inorganic peroxides and UVC as useful methods for degrading the β-lactam antibiotic dicloxacillin.•Persulfates and UV-C/H2O2 showed high degrading action on the target pharmaceutical.•Methodologies based on theoretical calculations for the identification of reactive moieties on the DXC susceptible to radical attacks are presented.