The continuous lumping approach was used for modeling of hydrocracking of heavy crude oil at moderate reaction conditions. The model parameters were estimated from experimental results obtained in an isothermal fixed bed reactor at different temperatures (380-420 degrees C) and space velocity (1.5, 0.5 and 0.33 h(-1)) at constant pressure and hydrogen-to-oil ratio of 9.8 MPa and 5000 ft(3)/bbl respectively. Four model parameters showed linear trend with temperature whereas only one parameter remained almost constant. The optimized values of model parameters were employed to predict results obtained at different reaction conditions from which they were derived. Comparisons between experimental data and predictions using the continuous lumping kinetic model showed good agreement with average absolute error lower than 5%. (C) 2009 Published by Elsevier B.V.