Thermogravimetric analysis coupled to Fourier transform infrared spectroscopy, TGA-FTIR, has been used real time to probe the degradation of polyamide 6 in highly pure N2 with constant rate-controlled heating(10 ℃/min). The results showed that the thermal degradation of polyamide 6 occurs in the range of 320-490 ℃. The amount of residue is 2% at 550 ℃. The evoloved gases, mainly H2O, CO2, aliphatic hydrocarbons and oligomer were determined. The presence of aliphatic hydrocarbons and oligomer indicates that under these conditions alkylamide bond (CH2—NH—CO) scission might occur either by homolytic cleavage or by cis-elimination in the case of polyamide 6.