The present work reports the synthesis of beta zeolite and its modification with phosphorous in different percentages of P2O5 (1 and 5%) and vacuum gas oil (VGO) hydrocracking (HCK) conversion and yield to naphtha and middle distillates. The solids were characterized by X-ray diffraction, elemental analysis by atomic absorption spectroscopy and inductively coupled plasma atomic emission spectrometry (ICP-AES), N-2 adsorption, Al-27 magic angle spinning-nuclear magnetic resonance ( Al-27-MAS-NMR), temperature-programmed desorption of ammonia (NH3 -TPD) and isopropylamine (IPam-TPD), pyridine adsorption followed by Fourier transform infrared spectroscopy (Py-FTIR), hydrogen temperature programmed reduction, transmission electron microscopy, and energy-dispersive X-ray (TEM-EDX). The catalysts were tested in a tubular reaction system at 350 degrees C, 10 342 kPa, H-2/feed: 1250 NL/L, LHSV: 1 h(-1)with prehydrotreated VGO. Overall activity and middle distillates and naphtha yields were influenced by the phosphorous impregnation on beta zeolite. Between 4 and 6% higher conversion was observed. Textural and acid properties were modified by the phosphorous treatment leading to a total acidity and surface area decrease with phosphorous content. Relative changes in tetrahedral and extra-framework aluminum were followed by Al-27-MAS-NMR. Al-((4)) assigned to distorted extra-lattice tetrahedral aluminum and Al-O(2) extra framework aluminum increased with phosphorous impregnation. Strong acidity monitored by IR of adsorbed pyridine showed a direct correlation with VGO conversion and naphtha yields.