The goal of the research described in the paper is to study co-firing of wood pellets and gaseous fossil fuel, evaluating the influence of co-firing on efficiency, produced energy volumes, and emission production. In order to achieve the set aim and objectives a special pilot device for wood pellets and propane/butane co-firing was constructed in an accredited laboratory. The results of the experimental research allow running a complete analysis of cofiring and evaluating the influence of magnetic field on efficiency, produced heat energy volumes, and emission production. The research has a high practical significance and is aimed to increase the level of wood biomass use for energy production as well as to ensure its effective application.