The effect of space velocity (WHSV) has been studied in the single-step hydrocracking of the LCO (Light Cycle Oil) obtained as byproduct in catalytic cracking (FCC) units, over a bifunctional catalyst of Pt-Pd supported on a high acidity HY zeolite. Accordingly, the hydrocracking and hydrodesulphurization conversions and. yields of product fractions (medium distillates, naphtha. LPG and dry gas) have been determined. The reaction conditions have been 350 degrees C, 45 bar, H-2/LCO molar ratio of 10. The catalyst reaches a pseudoestable state subsequent to a rapid initial deactivation and maintains a significant activity in this state for the production of medium distillates and naphtha. Studies have been carried on the composition of these streams and their interest for adding to the pools of diesel and gasoline. The results are encouraging for the upgrading of LCO by its hydrocracking over noble metal catalysts, given that they are of high activity. (C) 2011 Elsevier B.V. All rights reserved.