Three samples of gamma-Al2O3 with different textural characteristics have been synthesized from AlOOH powders (Sasol). Ni(Co)Mo/Al2O3 catalysts have been prepared by single impregnation of the gamma-Al2O3 samples with solutions of active ingredients. The morphology of the active phase of the sulfided samples has been studied by high-resolution transmission electron microscopy. The catalytic activity has been measured with the use of vacuum gas oil (VGO) as a feedstock at temperatures of 360, 390 and 420A degrees C. After catalytic activity measurements, the catalysts have been investigated by means of differential thermal and thermographic analysis (DTA-TGA). Textural characteristics of the catalysts in the oxide and sulfide forms have been determined, including those after the measurement of activity in VGO hydrotreating. The textural characteristics of the samples have been shown to correlate with the extent of the hydrogenation reactions of aromatic hydrocarbons and hydrodesulfurization. The highest hydrogenating and hydrodesulfurizing activity has been displayed by the sample on the support with the largest specific surface area and the smallest effective pore radius.