Thermal cracking of residual fractions has gained interest of refiners due to increasing demand of middle distillates and at the same time decline in demand of fuel oils. The present study is an attempt to gain deeper insight into the thermal cracking behavior of residual feedstocks in terms of certain key characteristics. Laboratory scale experiments on a 400 ml capacity stainless steel batch reactor were conducted with four residual feedstocks of Indian and Middle East origin-North Gujarat short residue (NGSR), Visbreaker feed from Mathura refinery (MVBF), Bombay High short residue (BHSR) and Asphalt from Haldia refinery (HRA), with asphaltene content varying in the range 1.85-10.15 wt%. The cracked products were separated by distillation up to 500 degreesC. The distillate (500 degreesC-) was analyzed by ASTM D2887 (SIMDIST) method and obtained data were classified into lumps, namely Gas (C-5-), Gasoline (IBP-150 degreesC), Light Gas Oil (150-350 degreesC) and Vacuum Gas Oil (350-500 degreesC) prior to detailed data analysis. The analysis of results reveals that the thermal cracking of petroleum residues follows first order kinetics. The rate constants and activation energies have also been estimated. (C) 2004 Elsevier Ltd. All rights reserved.