Thermogravimetry was applied to evaluate the heavy distillation residues of different Brazilian crude oils. The thermal characteristic of the samples could be studied by only one experiment. It was possible to evidence the linear correlations among the results obtained by the TG curves and by the patterned methodologies, therefore anticipating volatile and carbonaceous materials (coke) formed during their thermal cracking. The correlations herewith observed, in a short period of time, provided comparisons among the petroleum fractions. (c) 2005 Elsevier Ltd. All rights reserved.