<p>This study investigates the characterization and treatment of landfill leachate (LL) from the Mediouna landfill in Morocco. The effectiveness of the photocatalysis process using TiO₂-P25 under UV-A and UV-C irradiation was assessed as a post-treatment for the pretreated LL by coagulation-flocculation (C-F) with FeCl₃ coagulant. First, the LL pretreatment using C-F reduced turbidity, COD, BOD₅, UV₂₅₄, and color to 86%, 51.4%, 99%, 84%, and 82%, respectively. Then, the photocatalytic process conducted under optimized conditions of 1 g/L of TiO₂ at pH 4, 25°C led to a COD removal of 94% and 73% and UV₂₅₄ reduction of 97% and 80% under UV-C and UV-A, respectively. The constant kinetic rates reached 1.06 × 10^–2 min⁻¹ using UV-C and 0.34 × 10^–2 min⁻¹ using UV-A. On the other hand, the parameters influencing the photocatalytic treatment of pretreated LL under UV-C irradiation were optimized by Central Composite Design (CCD), where the high COD removal of 96.5% was achieved under optimal conditions, with COD_i of 1031 mg.L⁻¹, a TiO₂ mass of 1.2 g.L⁻¹, and a pH of 5.7. The findings highlight the potential of TiO₂ photocatalysis under solar light for effective LL treatment, offering an environmentally friendly alternative for the post-treatment of pretreated landfill leachates.</p>