Offshore process vessels of the oil/gas industry operate at high temperatures and sometimes high pressure. Protective coatings designed for high-temperature vessels need to withstand very high temperatures, e.g., higher than 200°C (392oF). The evaluation and determination of their fitness for use at such high-temperature conditions are challenging. In this paper, we demonstrated the use of multiple analytical methods (DMA, DSC, Dilatometer) in the investigation and characterization of structure stabilities of protective coatings in high temperature environment. We analyzed 3 coating samples by DMA with temperature ramping, thermal cycling experiments and thermal stress test. The results of DMA, combined with that from DSC, Dilatometer and mechanical tests provided us deep understanding of high temperature properties of the 3 coating samples. The study also explained the cause of cracking failures of 2 of the samples at different high temperature conditions. The methodology of this paper provides a good way to guide future development work and failure root cause analysis of protective coatings for high temperature applications.