NOVELTY - Two hydrogen storage units chosen from a gaseous hydrogen storing unit, liquid hydrogen storing unit and unit for storing solid hydrogen by absorption or adsorption are coupled and used in a single tank, for storing hydrogen in a hybrid form. Each unit is sized to store at least 5 weight.% of the total amount of hydrogen stored within the tank.    USE - For storing hydrogen in a hybrid form, for hydrogen-powered automotive vehicle.    ADVANTAGE - The hydrogen storage method permits fast release of hydrogen whenever required and ensures high storage capacity. Refilling up of a hybrid tank is perform in reduced time compared with conventional metal hydride tank.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a hybrid tank (11) for storing hydrogen in both liquid and solid forms or gaseous and solid forms. The hybrid tank for storing hydrogen in liquid and solid forms comprises two concentric containers with an inner container for storing hydrogen in a liquid form located in an outer container. The containers are separated by an insulating sleeve for maintaining the inner container at low temperature. The outer container is in direct communication with the inner container and contains a metal hydride for storing hydrogen in a solid form. The hybrid tank for storing hydrogen in solid and gaseous forms comprises a container having a metallic liner or inner wall (15) covered with a polymeric outer shell (13). The container is devised to store hydrogen in gaseous form at high pressure and to receive and store the metal hydride for storing hydrogen in solid form. At least one heat pipe (19) is mounted in the container to allow circulation of a heat carrying fluid within container. A heat exchanger is located within the container to ensure thermal connection between at least one heat pipe and the hydride.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic cross-sectional view of the hybrid gas-solid storage tank.    Hybrid tank (11)    Polymeric outer shell (13)    Metal liner or inner wall (15)    Axial opening (17)    Heat pipe (19)    Metallic grid, fiber or porous structure (21)