This study investigates the possible synergistic interactions between the Sudanese lower sulphur petroleum coke (PC) and sugar cane bagasse (SCB) during H2O co-gasification with three concentration values (25%, 50% and 75% v/v) using a thermogravimetric analyser (TGA) at 20 degrees C/min. The kinetic thermal behaviour, and effects of both H2O concentration and fuel blending ratio were investigated. The results show that, significant interactions existed in both reaction stages of samples, and become less when PC content and H2O concentration are 50%. Petroleum coke showed only one char gasification stage at (>700 degrees C) at 75% H2O. Some kinetics models like homogeneous and shrinking core models were studied by the Coats-Redfern method in order to observe the optimum reaction mechanism for the H2O gasification of samples, describe the best reactive behaviour and determine the kinetic parameters. The results showed that, the co-gasification behaviour and kinetic parameters have a significantly influenced by increasing both H2O concentration and PC content. The boundary controlled reaction model (R2) shows the lowest values of activation energy (E) for all samples and H2O concentrations. Finally, all the models are successfully utilized to predict the experimental data under all H2O concentration values. (C) 2013 Elsevier Ltd. All rights reserved.