In this work the degradation process of polyamides (PAs) based on renewable resources - PA 4.10, PA 6.10, PA 10.10 and PA 10.12, was studied by thermogravimetry (TG) coupled with evolved gas analysis (EGA) by infrared spectrophotometry (IR), quadrupole mass spectrometry (QMS). The TG/FTIR/QMS studies in inert atmosphere showed that the thermal decomposition of bio-polyamides takes place with the evolution of alkenes, nitriles, cyclic species and low molecular weight compounds - carbon monoxide, carbon dioxide, water and ammonia. The thermo-oxidative decomposition of bio-polyamides start with N-vicinal methylene group and follow with the scission of alkyl-amide or vicinal C-C bond. The high energy reactions result in production of mainly low molecular gases (CO2, CO, H2O, NH3). Char residue analysis revealed the presence of carboxylic end groups, which may participate in secondary reactions during degradation, resulting in crosslinks, and decomposing to carbon dioxide. Taking into account the thermoanalytical results obtained, the thermal decomposition pathway for bio-polyamides in inert atmosphere has been postulated. (C) 2015 Elsevier B.V. All rights reserved.