Abctract The aim of this work is to explore the floculation behavior of asphaltenes (extracted from a deposit recovered from a Hassi-Messaoud oil well) in solution in toluene according to the polarity of the flocculating medium. The flocculation thresholds related to the addition of two flocculating agents of different polarities (n-heptane and acetone) for three asphaltenic concentrations are obtained by means of near infra-red absorption spectrophotometry. The Hildebrand solubility parameters of the flocculated asphaltenic fractions are deduced using the Donnagio method based on the Flory-Huggins theory. The results obtained indicate that the interactions between the flocculated asphaltenic molecules within the toluene/acetone mixture are weaker than those in the toluene/n-heptane mixture.