Flash pyrolysis experiments of sunflower (Helianthus annuus L.) press oil cake were performed in a tubular transport reactor at atmospheric pressure under nitrogen atmosphere. The effects of pyrolysis temperature, particle size and sweep gas flow rate on the yields of products were investigated. The temperature of pyrolysis, particle size and sweep gas flow rate were varied in the ranges 450-700 degreesC, D-p < 0.224, 0.224-0.425, 0.325-0.850 mm and 25-600 cm(3) min(-1), respectively. The maximum oil yield of ca. 45% was obtained at a pyrolysis temperature of 550 degreesC, with the sweep gas flow rate of 300 cm(3) min(-1) and particle size of 0.425-0.850 mm. The elemental analysis and calorific value of the pyrolysis oil were determined, and then the chemical composition of the oil was investigated using chromatographic and spectroscopic techniques (H-1 NMR, IR, column chromatography and GC). The chemical characterization has shown that the oil obtained from sunflower oil cake can be used as a renewable fuel and chemical feedstock. (C) 2001 Elsevier Science B.V. All rights reserved.