Biomass as an energy source has a lot of advantages over fossil residues, but it presents an important drawback: in local environments, such as homes, people are exposed to some harmful gases evolved during the biomass degradation process. Thus, many efforts have been made in order to dismiss these pollutants, being the blending with less pollutant biomass materials (that is, dilution), the optimization of the energy obtaining process and the use of catalysts and adsorbents the most popular ways to achieve this goal. The aim of this research was to assess the effectiveness of dilution over grape pomace, a quite abundant residue in Extremadura (Spain), blending it with Pyrenean oak. During the combustion of these blends, some parameters were measured by a coupled TG-MS technique, which allowed us to obtain much information about kinetics and evolved gases emissions. It is shown how the dilution effect affects both the amount of evolved gases (reducing them) and the combustion mechanism. (C) 2011 Elsevier B.V. All rights reserved.