Hydrogen is expected to be highly valuable energy carrier for the 21 th century as it should participate in answering main society and economical concerns. To exploit the benefits of this energy at large scale, further research and technological developments are required to secure its storage, especially during fire exposure. Thus, studies on the thermomechanical behaviour of the composite used in the manufacture of tanks for the storage of hydrogen are important. At present, the use of epoxy/carbon fibre composites is developed widely because of its low weight and its good mechanical properties. Thus, the present study focusses on the thermal decomposition property and the influence of a fire or a heating source on the residual mechanical behaviour of such materials. To account for this point, an experimental study is introduced to improve the understanding of thermal decomposition and fire exposure mechanisms of composite using different "elementary" samples. Firstly, to characterize the mechanical properties versus fire exposure, a thermal degradation is performed using a cone calorimeter on composite samples. These tests are led for various heat flux values and are stopped at different characteristic times. Then, the mechanical properties are characterized using tensile test on samples submitted at first to different fire time exposure. The evolution of the elastic properties and ultimate stress show that the density of energy is the main factor leading to a change of the mechanical properties and char thickness evolution. Secondly, to characterize the mechanical properties versus temperature, tensile tests are performed on samples submitted in situ to 4 homogeneous temperature conditions up to 150°C. Finally, A thermomechanical model is proposed to predict the behaviour of composite material.