The sp(2)-to-sp(3) carbon bonding character in asphaltenes that results from heavy crude visbreaking was evaluated by means of X-ray photoelectron spectroscopy (XPS), photoelectron energy loss spectroscopy (ESCALOSS), X-ray excited Auger spectroscopy (XAES), and time-of-flight secondary ion mass spectrometry (TOF-SIMS). The asphaltenes were precipitated from virgin Doba-Chad heavy crude or from treated crudes after undergoing noncatalytic and (FeS and MoS2 mediated) catalytic hydrovisbreaking to reduce heavy crude viscosity for meeting pipeline transportation specifications. The sp(2) and sp(3) characters of the asphaltenes were calibrated using, respectively, highly oriented pyrolytic graphite (HOPG) and diamond. Composites of asphaltenes with polyethylene and polystyrene references were used to assess the shift from sp(3)- to sp(2)-dominated structures. It was postulated that the T aromatic character in the asphaltenes condensed polynuclear aromatic rings correlates with sp(2) carbon, whereas the asphaltenes aliphatic character correlates with sp(3) carbon. Percentages of sp(2) sites ranged between 36% and 70% for all the asphaltenes samples with values from XPS being underestimated, with respect to XAES. The splitting between the principal nonloss C 1s line and the largest plasmon loss peak, and the evolution in shape of the pi-->pi* plasmon satellite in the energy loss spectra were in qualitative agreement with XPS and XAES data. In addition to aromatic and aliphatic hydrocarbon ion fragments, the high sensitivity of TOF-SIMS allowed the detection of several hetero-elements (such as nickel, vanadium, sulfur, and nitrogen, in the organometallic-bearing asphaltenes, or iron, chlorine, sodium, potassium, and silicon, as foreign elements). Probing the surface composition through the SigmaCH(x)(+)/C-2(+) ratio indicated that asphaltenes were bearing more aliphatic character than the carbon blacks or graphite, presumably because of the presence of hydrogen during hydrovisbreaking. However, surface probing via the C2H-/C-2(-) ratio suggested that asphaltenes were less aromatic, as expected, than graphite while exhibiting an aromatic character close to that of some carbon blacks.