Problems related to the combustion of heavy oils with high vanadium contents in a high-capacity steam boiler have been analyzed. In this study, two types of additives have been tested both to diminish high-temperature corrosion and to obtain more brittle deposits. Results show that heavy fuel oil can be suitably burned in this type of boilers if it is chemically treated with an anticorrosive additive. In this research, the best results have been obtained when the heavy fuel oil was mixed with an organometallic additive. The influence of fouling on the behavior of some operational parameters such as the pressure in furnace and pressure drop in superheaters and pipe metal temperature, among others, has been verified. It is concluded that monitoring of these parameters can provide direct information on the degree of fouling, as well as of the effectiveness of the treatment during normal boiler operational conditions. Some other improvements in the atornization and combustion processes due to the use of the organometallic additive have also been observed. (C) 2004 Elsevier B.V. All rights reserved.