In this work, the evolution with temperature of the qualitative composition of the gases evolved in the pyrolysis of glycerol, tobacco and tobacco-glycerol mixtures has been studied. The pathways for different types of compounds (i.e., water, CO, CO2, carbonylic compounds, alkenyl or alkyl groups containing compounds, alcohols and phenols and aromatic compounds) have been established, and their relationship with the different reaction steps involved in the pyrolysis process have been suggested. The comparison among the behavior observed in the pyrolysis of tobacco, glycerol and a mixture glycerol-tobacco has permitted us to suggest possible interactions between tobacco and glycerol affecting the composition of the gases evolved. (C) 2013 Elsevier B.V. All rights reserved.