In this work, a cost-benefit analysis concerning the use of fuel oil additives in heavy fuel oil fired water tube boilers is performed. The properties of various additives are discussed and their advantages and disadvantages outlined. Finally, the possible use of additives within a generation system and the cost implications are examined. Based on the market survey, it can be concluded that FO additives can prove beneficial, both technically and financially. (C) 2003 Elsevier Ltd. All rights reserved.