Polyamide 6 (PA6) is modified with a nanoclay (NC), Cloisite 30B and/or a flame retardant (FR), OP1311. The thermal decomposition of pure PA6 and PA6 nanocomposites is done by thermogravimetric analysis (TGA). The decomposition products from TGA in nitrogen and air are analysed online by Fourier transform infrared (FTIR) spectroscopy in order to examine the time/temperature-dependent thermal degradation processes and monitor the evolved gases online. The profiles of the evolved gases are compared with epsilon-caprolactam spectra, which are the main species in the gas phase. Results show that the addition of the fire retardant decreases the degradation temperature, whereas the incorporation of NC (PA6+NC) contributes to increased residual mass and char formation. The evolved gases from TGA-FTIR in nitrogen from pure PA6 and (PA6+NC) are hydrocarbons, carbon dioxide, water, epsilon-caprolactam and ammonia. The (PA6+FR) and (PA6+NC+FR) evolve the same volatiles with an additional phosphorus-containing species, namely diethylphosphinic acid. The thermo-oxidative degradation of all these composites in air yields carbon monoxide with an increased production of carbon dioxide, water and hydrogen cyanide. Another important result is that the hydrogen cyanide does not increase when the phosphinate FR is used. Copyright (C) 2009 John Wiley & Sons, Ltd.