The disposal of waste materials using incineration methods is becoming increasingly important from the view point of the need to minimise the environmental impact of sewage sludge disposal. This investigation has involved the use of temperature programmed combustion (TPC) to study the interaction between coal, polyethylene, and dried sewage sludge which are possible components in coal/ waste materials co-processing combustion systems. The TPC studies were carried our on the raw materials and 1:1 mixtures of sludge/coal and sludge/polyethylene. Comparison of the gas evolution profiles of the mixtures with corresponding profiles obtained by the summation of the profiles of the component materials indicate that there were interactions between the mixtures during the combustion. Significant interactions may occur when the combustion temperature ranges of the materials overlap.