The Jatropha curcas fruit shells (JCFS) and Jatropha curcas seed cake (JCSC) have drawbacks when used as fuel, namely flame front instabilities and short combustion periods. In this work, a blend of 25 wt% Jatropha curcas pellets with 75 wt% of pruning residues (PR) resulted in a fuel mixture that promote a stable flame front and the combustion process could be sustained for periods larger than 60 min. The improvement in the combustion of the blend composed of Jatropha curcas pellets and PR, when compared to mono-combustion of Jatropha curcas pellets, can be explained in result of the better fuel properties given by PR to the fuel blend. It was observed that PR combustion is associated to higher temperatures in the flame gases and the CO concentration in the flue gas is less than 1500 mg/Nm(3) (dry gases, 13% vol. O-2), thus in accordance to the European standards for solid fuel stoves. Although the PR fraction in the biomass mixtures is high (75 wt%), the observed CO concentration in the flue gas during combustion of the fuel blends was higher than 1500 mg/Nm(3) (dry gases, 13% vol. O-2) especially in the fuel mixtures that incorporate JCFS in their composition. (C) 2019 Elsevier Ltd. All rights reserved.