We investigated the thermal decomposition behavior of three commercially available liquid crystalline polymers (LCPs), Vectra A950, Vectra B950, and Xydar SRT-000. The apparent activation energies (E-a) associated with the thermal degradation processes were determined by the Ozawa and Kissinger methods, using data from dynamic thermogravimetric analysis (TGA) experiments. The magnitudes of the E-a for these LCPs follow the order: Xydar > Vectra A > Vectra B in both air and N-2 environments. The stability of the samples at the beginning of the degradation processes follows the same order. This order may result from the kink naphthoyl units in Vectra A and a relatively weak bond dissociation energy of C-N in Vectra B. However, at 560 degrees C the weight loss values of these three LCPs in N-2 become close (around 37%). After 600 degrees C, the stability order surprisingly changes to Vectra B950 > Vectra A950 > Xydar SRT-900. This suggests that the more stable the sample is at the beginning, the less stable the corresponding residue is. Fourier Transform Infra-red (FTIR) spectra imply that random chain scission and hydrogen abstraction are the degradation mechanisms in N-2 atmosphere and the bands of C=O stretching for all 3 LCPs decrease after 560 degrees C, indicating the finish of the ester bond rupture process. Further increasing temperature mainly results in carbonization. For all three LCPs, CO, is the dominant degradation product during the entire testing periods in both Nz and air environments and the change of CO, amount is consistent with the degradation rate. Residues after TGA experiments in N-2 were analyzed and found to have a relatively high percentage of oxygen element, indicating the formations of ether and ketone structures during the thermal degradation of these three LCPs. Forty-seven percent of the nitrogen element remaining in the case of Vectra B950 indicates the formation of the structures containing nitrogen.