A rapid method for the determination of asphaltene content in bitumens, heavy oils, and distillation residues using thin layer chromatography (TLC) and colorimetry is described. The method determines the weight percent of asphaltenes defined as the portion that is insoluble in n-paraffinic solvents and soluble in toluene. It is applicable to all light and heavy oils, bitumens, and petroleum distillation residues (pitches).