The deactivation of noble metal catalysts has been studied in the hydrocracking of the Light Cycle Oil (LCO) obtained as a byproduct in FCC units. The catalyst metallic functions are Pd, Pt, and Pt-Pd, which are supported on acid materials of different porous structure and acidity (HY zeolite, Hβ zeolite, amorphous alumina, and an FCC catalyst). The reaction conditions are 350 °C; 50 bar; H2/LCO molar ratio (nH2), 8.9 mol H2 (molLCO)-1; space velocity (WHSV), 4 h -1; time on stream, 300 min. The roles of the metallic function, porous structure of the support, and, particularly, catalyst acidity in the deactivation by coke deposition have been studied. Deactivation leads the catalyst to a pseudostable state, with significant activity remaining when a support with high acidity is used (a HY zeolite with SiO2/Al 2O3 = 5) and a better performance of the Pt-Pd metallic function. © 2011 American Chemical Society.