This report summarises data on the production and use of coal ash in different countries and the discernable trends in the approach to ash use. It investiages the physical and chemical characteristics of coal ash resulting from changing practices in plant operation in response to the demands of environmental regulations. THe influence of fuel characteristics is summarised, including the effects of co-firing coal with other materials such as biomass and wastes. Effects due to changes in boiler operation are covered as well the optimised use of reagents and additives in particulate, SO2 and NOx emissions control systems to maintain . . .