According to the recent environmental constraints, thermal solar power plants are currently under worldwide expansion (400 MWe are already under exploitation, 500 MWe are planned for the next few years). French industrials partners involved in the group SOLTEC have pronounced their common will to invest in those technologies and to build such plants within the Mediterranean area. Two main industrial activities can be considered as potential in France : - realisation and exploitation of solar power plants in France or abroad (a French technology would be exported), - conception, development and commercialisation of efficient subunit systems for the future plants. The SOLSTOCK project contributes two both of those perspectives in term of enhancement of the acceptability and rate of those processes through the achievement of a key subunit: an innovative thermal storage adapted to the future solar power plants of high concentration level. This project is based on the development of innovative and original materials, know-how and technology: the subunit system is composed of an innovative composite material, an optimized exchanging envelop and their integration to the whole process. According to the high temperature level (about 1000°C) as well as the high thermal flux level (about 250kW/m2), a specific study and the development of adapted characterisation tools are needed. This project would also lead to a better management of the solar plants: the excess heat available in the middle of the day will be shift to the peaks of demand of the evening or the morning. The need in backup based on fossil energy sources will be lowered and consequently, the production of greenhouse gas will be decreased. To reach this performance, the solar plants in which has been integrated the storage unit has to be managed efficiently. This particular aspect will be also developed during the project on the basis of the current know-how of the industrial partner. In the project are gathered 3 partners: the CRMHT laboratory acknowledged in the field of high temperature molten salts, the PROMES laboratory specialised in concentrated solar processes and CRISTOPIA, worldwide leader in industrial latent heat thermal storage. The phase change material used on the storage system will be an inorganic salt. At this temperature level, the characterization and the understanding of the molten salt properties and behaviour are rather difficult and of particular importance for the project. According to its corresponding knowledge, the input of the CRMHT laboratory in this field will be particularly needed. For a decade, the PROMES laboratory has studied highly conductive composite materials devoted to thermal storage while CRISTOPIA has developed a very complementary approach based on heat transfer interface intensification.