In the present work. a quantum mechanics parametric method was employed to evaluate the interaction of metallic nickel, potassium, and water with an asphaltene model molecule (AMM). A reaction scheme is proposed for a catalytic steam cracking (CSC) process based on the formation and breaking of bonds. It was found a very important interaction between metallic nickel with nitrogen, and sulfur atoms of the asphaltene molecule, which leads to the formation of nickel-asphaltene intermediate complexes. Also, it was observed that nickel-asphaltene complexes are able to dissociate water and in such cases asphaltene molecules may be hydrogenated. Electron transfer from potassium to asphaltene systems promotes the H2O dissociation on Ni and favors C-S and C-N bond activations. (C) 2004 Elsevier B.V. All rights reserved.