Thermal decomposition processes were investigated for Bacillus Gram-positive spores. Thermogravimetry analysis (TGA) experiments at 200 K min(-1) produced a temporal evolution of biochemicals from the spores. Qualitative and quantitative aspects such as peak resolution, peak ratios, peak positions, and temperature maxima are compared and contrasted in the thermal weight loss and differential thermogravimetry (DTG) curves for different Bacillus bacterial spores. The TGA experimental data were used to generate the activation energy and frequency factor Arrhenius equation parameters. These parameters were used to produce TGA and the negative of the first derivative of the TGA (-DTG) decomposition model curves, and the latter are compared to their respective bacterial experimental TGA and -DTG profiles for validation and modeling purposes. The thermal decomposition model is also shown to have application in the prediction of weight loss profiles at significantly higher heating rates than that from the laboratory TGA system. The model thermal decomposition profiles are applied in comparisons to the total ion chromatograms of Bacillus atrophaeus bacterial spores generated by an outdoors fielded pyrolysis-gas chromatography-ion mobility spectrometry (Py-GC-IMS) bioaerosol detection system. Pyrolysis at a high heating rate of 3300 K min-1 was used. The bioaerosol detection system provides very similar qualitative information to the TGA and -DTG experimental and model profiles. (C) 2005 Published by Elsevier B.V.