A method is described in which the time taken for molecules evolved during simultaneous TC-DTA analysis to travel from the sample crucible to an evolved gas analysis (EGA) detector, defined as the transfer time, tau, may be determined. It involves heating a <45 mu m fraction of pyrite to about 550 degrees C at a rate of 2.5 degrees C min(-1) in air flowing at rates ranging from 8 to 91 cm(3) min(-1) in a thermal analyser and passing the SO2 evolved into a Fourier transform infra-red Fm) or mass spectrometer (MS). Two sharp exothermic events occurred in the region 455-475 degrees C which corresponded to equally sharp peaks in the FTIR and MS signals. The time shift between the DTA peak and the corresponding EGA peak was taken to be the transfer time and it was found that this increased with reduction in gas flow rate. For the equipment used in this experiment transfer times of SO2 produced during the two events agreed within experimental error for gas flows down to 20 cm(3) min(-1) but significant differences were measured for lower flow rates. This method should be useful in determining the transfer times of any combination of thermal analyser and FTIR or MS, provided the thermal analyser has a DTA detector.