Hydrogen storage is an important issue for the hydrogen economy development. The aim of this technological challenge is to store with safety the maximum of gas in a minimum of volume or mass of storage system. Nowadays the most popular storage method is based on compressed hydrogen gas. High pressure storage gas is performed by Type III or IV Tanks. These types of tanks have both a composite part to give the mechanical strength but Type III has a metallic liner when Type IV has a Polymer liner. The static burst pressure of both tanks must be in accordance with the requirements of the standards which give the safety coefficient between burst and working pressure. The safety coefficient is depending on the type of composite and the type of application, but increases the final price of the tanks. The design of the composite structure which satisfies this safety coefficient can be considered as optimal if the mass of composite is minimum. This paper deals with the search of this optimal structure. Based on mechanical considerations, a model is proposed for stresses assessment of the cylindrical section of the vessel under thermo-mechanical static loading. The liner is assumed to behave as an elasto-plastic material (metallic) or elasto-visco-plastic (polymer) whereas the laminate is an elasto-damageable material. The stresses in each material are provided by the model. An anisotropic failure criterion can be used for predicting burst pressure. This model is a part of a Computer Aid Design of composite structure of tanks.