Temperature-programmed co-pyrolysis of Goynuk-oil shale (GOS) with Sirnak-asphaltite (ASP) from Turkey was investigated. The aim of this research was to determine the volatile product distribution and product evolution rate of co-processing of GOS with ASP. A series co-pyrolysis operation was performed with GOS and ASP using a 1/2, 1/1, 2/1 total carbon ratio of GOS to ASP. A fixed-bed reactor was used to pyrolyse small sample of GOS and ASP mixture under an inert gas flow (Argon). A special sampling technique was used for collecting organic products eluted from the reactor at different temperature and time intervals. The co-pyrolysis products were analyzed by capillary gas chromatography and the total product evolution rate was investigated as a function of temperature and time. n-Paraffins and l-olefins in aliphatic fraction of pyrolysis products were classified as a carbon number. In addition, the recovery of total organic carbon as an organic volatile product was determined. The assessments were based on incorporating the results on temperature-programmed pyrolysis of GOS and ASP. The effect of co-processing of GOS with ASP was determined by calculating the difference between the experimental and the hypothetical mean value of conversion of total organic carbon into volatile products. (C) 2002 Elsevier Science Ltd. All rights reserved.