A Fourier transform infrared spectrometer (FTIR) was coupled to thermogravimetric (TG) experimental equipment to determine the products of the thermal decomposition of several biomass samples both qualitatively and quantitatively. Working conditions for the TG device were simulated in a CFD model to analyse gas flux difficulties, embedding different models included in ANSYS FLUENT 12.1.4, including programming temperature control and devolatilisation kinetics, through User-Defined Functions. Based on the CFD results, an improvement to the experimental equipment was designed, simulated and implemented. A comparison between data from the original and the improved equipment was performed, including both experimental and simulated data. (C) 2011 Elsevier Ltd. All rights reserved.