The effect of deasphalting of heavy oil with different degrees of asphaltenes precipitation on catalytic hydrotreating is reported in this work. Deasphalted oils were obtained in a pressurized vessel using n-heptane and n-pentane as solvents. Various samples with different amounts of asphaltenes were prepared by varying precipitation conditions. Hydrotreating of deasphalted oils was conducted with a commercial NiMo catalyst in a batch reactor at the following reaction conditions: hydrogen pressure of 100 kg/cm(2), temperature of 400 degrees C, stirring rate of 750 rpm and reaction time of 4 h. The heavy oil, the deasphalted oils and the hydrotreated products were characterized by sulfur, metals (Ni, V), asphaltene contents, and API gravity. Metals and carbon contents as well as textural properties and X-ray diffraction were also determined on fresh, spent and regenerated catalysts. (C) 2009 Elsevier B.V. All rights reserved.