Spain, like most European countries, faces serious problems of pollution of its water resources. Currently, research is focused on the development of an effective, innovative and environmentally friendly treatment, such as heterogeneous photocatalysis, for the elimination of pollutant residues from these waters. In this work, the photocatalytic degradation of triazine (atrazine, simazine and terbuthylazine) and phenylurea (chlortoluron, diuron and isoproturon) herbicide residues was assessed in three different real wastewater effluents. A photochemical reactor was used to conduct the experiments at laboratory scale with TiO₂/Na₂S₂O₈ in water exposed to UV-A irradiation from light-emitting diode (LED) lamps. Herbicide residues were analysed by high performance liquid chromatography-tandem mass spectrometry (HPLC/MS²) and their degradation followed single first-order kinetics. Results showed that TiO₂/Na₂S₂O₈/UV-A/LED is a suitable alternative for tackling the removal of the studied herbicides from wastewater.