The invention relates to a novel hydrocarbon hydroconversion catalyst. This catalyst is a mixture of a matrix and a zeolite, the zeolite having a molar ratio SiO2/Al2O3 comprised between about 8 and 70, a sodium content below 0.15% by weight, a parameter a of the elementary mesh comprised between 24.55x10-10 m and 24.24x10-10 m, a sodium ion take-up capacity CNa expressed in grams of sodium per 100 grams of the modified zeolite, higher than 0.85%, a specific surface higher than 400 m2.g-1, a water vapor adsorption capacity at 25 DEG C. (at a P/Po ratio equal to 0.10) higher than 6%, a pore distribution comprised between 1 to 20% of the pore volume, contained in pores of diameter situated between 20 and 80x10-10 m, the remainder of the volume being essentially contained in pores of diameter less than 20x10-10 m. The pore volume V (desorption isotherm of nitrogen) and the micropore distribution DV/dD are demonstrated particularly in FIG. 1.