Asphaltenes derived from Athabasca and Utah oil sands have been characterized using different techniques. Several factors were found to differentiate these asphaltenes. Number average molecular weight of Utah asphaltene was significantly higher, which correlated with its higher light absorbing capacity, compared with that for Athabasca asphaltene. In Athabasca asphaltene, V and Ni were higher and Al, Mn, Mg, Ca, Ti, Fe were lower than those in Utah asphaltene. Structural models for these asphaltenes, as determined using a combination of 1H and 13C n.m.r. spectroscopy, were different with higher aromaticity and degree of condensation of aromatic rings for Athabasca asphaltene. 13C structural parameters for humic acids extracted from demineralized fines separated from Utah oil sands were compared with Athabasca oil sand humic acid. As in the Athabasca sample, aromatic carbon in Utah humic acid was shown to be the predominant type of carbon.