The paper presents the study of thermal degradation of some [1,3,4]oxadiazole Schiff bases with alkyloxy and acyloxy terminal chain. The structure stability relationship based on TG-MS-FTIR investigations, the degradation processes and the influence of the type of terminal flexible chains upon the thermal and thermal-oxidative stability of 2,5-disubstituted-[1,3,4]oxadiazole derivatives with liquid crystalline properties were investigated. All the investigated compounds presented a very good thermal and thermal-oxidative stability, higher than 330 degrees C. Thermal stability was investigated both in nitrogen and helium atmosphere. Compounds with alkyloxy terminal chains proved to be more stable than the acyloxy analogous. (C) 2011 Elsevier B.V. All rights reserved.