Combustion is now one of the principal methods recommended for the disposal of the ever-increasing amounts of waste produced by modern society, but there is a conflict because of the need to reduce emissions to the atmosphere. The paper describes a systematic experimental study on the cocombustion of waste derived fuel and coal. Particular attention is given to the emissions of nitrogen dioxide. A relatively novel optical transmission method was used to determine the emission levels of NO2 in the exhaust flue. These measurements are complemented by thermocouple data for the gas temperature variations achieved during the combustion period. The results for a range of different waste derived fuel to coal mixtures are presented. These results enable the relationship between the combustion bed temperatures and the gaseous emission levels to be discussed.