By means of density fractionation, solids associated with bitumen derived from a variety of oil sand grades, were separated into fractions having different humic matter content. Elemental compositions (daf) and calculated densities of the different fractions were similar suggesting a similarity in the nature of the humic matter. Density fractionated solids having a low and a high (∗>87%) ash content were treated with NaOH for various periods of time to extract the humic acids. For all humic acids analysed the elemental composition and distribution of carbon types in each region of 13C n.m.r. spectra were similar. It has been shown that aromatic carbon was the predominant type of carbon for all samples. On the basis of the aromaticity data, it has been suggested that oil sand humic matter has a significant terrestrial input.