The intrinsic kinetics of asphaltenic metal and heteroatom removal reactions are reported. The asphaltenic sulfur, nitrogen, nickel, and vanadium were determined in isolated asphaltenes from raw material and products. The kinetic study was carried out at high temperatures (375-415 degreesC) and hydrogen pressure, 12.5 MPa, in a perfectly mixed reactor in continuous operation. Concentration data fit half-order kinetics with respect to asphaltenic sulfur, nitrogen, and metal (Ni and V) concentration, the activation energies being 35.6, 39.3, 47.7, and 45.3 kcal/mol, respectively.