© 2019 Elsevier Ltd This study investigated the use of a deep eutectic solvent (DES) for promoting the yield and stability of ceria nanoparticles used for the degradation of flumequine (FLU) under UV-C irradiation. The characterization by Fourier transform infrared spectroscopy, X-ray diffraction spectroscopy, Raman spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, high resolution transmission electron microscopy, thermogravimetric analysis, and BET surface area analysis revealed the synthesis of highly stable, highly crystalline, and mesoporous ceria nanoparticles using DES which led to the high removal, i.e., 50 % and 94 % of FLU using DES-Ceria and UV-C/DES-Ceria, respectively. Removal of FLU by the UV-C mediated ceria nanoparticles was due to [rad]OH and thus factors that influenced the reactivity and yield of [rad]OH retarded the removal efficiency of FLU. The pH of aqueous solution affected the removal of FLU by the photocatalysts and removal of FLU was inhibited at highly alkaline and acidic pH. The degradation pathways of FLU were established from the pattern of its degradation and nature of the degradation products. Acute and chronic toxicities of FLU as well as its products were measured. The photocatalyst synthesized in DES was found to be environmentally benign and showed significant potential in the remediation of FLU.