Fouling of tar in wood pellet boiler reduces its thermal efficiency and demands periodical maintenance to keep its original performance. The fouling of tar in wood pellet boiler was studied along with the physical and thermal characteristics of the pellets. Four different samples were prepared and accessed: a sample of control pellets without additives and three other samples each with 2% additives (dolomite and/or lime). Experiments for each sample were carried out in the pellet boiler for 20 h and fouling of tar is investigated. It is observed that the fouling of tar is drastically reduced in the pellets with additives 1% dolomite plus 1% lime: 76% by area-density (kg/m(2)) and 82% by thickness (mm). At the same time, the particle density, mechanical durability, bulk density, and heating value are also found to be improved leading to an improved overall performance of the pellets and the boiler. The pellets with the additives are, therefore, found to be a better option to reduce tar in wood pellet boilers and are recommended. (C) 2017 Elsevier Ltd. All rights reserved.