Despite the great utility of nanoparticles (NPs) in water remediation, their effects on marine ecosystems are unknown and unpredictable. The toxicity of the most used nanoparticles, such as ZnO, Ag, and TiO 2 on the purple sea urchin, Paracentrotus lividus (Lamarck, 1816), has been demonstrated by several authors. The aim of this study was to evaluate the effects of TiO 2 sol-gel and TiO 2-rGO nanocompounds on both vitality and motility of spermatozoa of P. lividus. The spermatozoa were exposed at different times (30 and 60 min) and concentrations (10, 20, 40 µg/mL) of both nano-TiO 2 compounds. The results clearly showed a decrease in both vitality and motility of P. lividus spermatozoa exposed. In particular, vitality and motility were inversely related to both exposure time and concentration of TiO 2 sol-gel and TiO 2-rGO nanocompounds.