The effect of pressure on the kinetics of the moderate hydrocracking of heavy oil has been studied in this work. Various experiments were conducted at pilot-plant scale at the following moderate operating conditions: pressure, 6.9-9.8 MPa; hydrogen:oil ratio, 5000 ft(3)/bbl; temperature, 380-420 degrees C; and space velocity, 0.33-1.5 h(-1). A kinetic model with 5 lumps (residue, vacuum gas oil (VGO), middle distillates, naphtha, and gases) and 10 rate constants was developed. The experimental data of the residue hydrocracking were well-adjusted to second-order reaction kinetics. Modified Arrhenius equations were used to include both pressure and temperature effects on the hydrocracking kinetics. Calculated product compositions were in good agreement with experimental values, with absolute average errors of < 5%.