The behaviour of nitrogen compounds during the liquefaction of dewatered sewage sludge was examined. After liquefaction (at 150-350 degrees C), the product mixture was separated into oil A (water-soluble). oil B (water-insoluble), aqueous phase and solid residue. Partition of nitrogen to oil occurred at > 150 degrees C. Above 150 degrees C, 60% of the nitrogen in the sewage sludge was transferred to the aqueous phase. Solubilization and decomposition of the nitrogen compounds were promoted at 150 degrees C. The distribution of nitrogen to oil B obtained by liquefaction at 300 degrees C was 9%, whereas that to oil A was 11%. (C) 1997 Elsevier Science Ltd.