NOVELTY - Preparing hydrogen comprises hydrolysis of solid SnO (tin (II) oxide) to produce hydrogen, where the produced hydrogen is stored, recovered and/or evaluated, and the implemented solid SnO is obtained by heat reducing of tin oxide (SnO2) into SnO in the conditions leading to SnO gas and cooling the produced SnO gas at a temperature of less than or equal to 550 degrees C.    USE - The process is useful for the preparation of the hydrogen.    ADVANTAGE - The process provides: hydrogen with high yield. The process is non-toxic and non-corrosive. The tin oxide is used in the process, hence cost effective. The process provides a good performance of both chemical and energy.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for:    (1) a device adapted in the implementation of step of the process comprising hydrolysis reactor (3) fitted with a first inlet (5) adapted in introducing of solid SnO in the hydrolysis reactor as obtained from reducing and cooling steps, an a second inlet (7) connected to water supply unit, and an outlet for evacuating produced hydrogen, and units for recovering and/or evaluating of formed hydrogen in the outlet of the hydrolysis reactor;    (2) a fuel cells comprising the device as hydrogen generator; and    (3) an installation for the implementation of the process comprising the device (1) associated with a reactor for reducing SnO2 into SnO equipped with a unit for supply related to an inlet for introducing SnO2 and an outlet adapted for evacuating SnO gas, and unit for cooling of gas stream comprising SnO gas connected to the outlet of the reduction reactor, suitable for a conversion of SnO gas into SnO solid, a units for supplying SnO solid obtained from cooling unit (28) connected to the first inlet of the hydrolysis reactor.    DESCRIPTION OF DRAWING(S) - The figure shows the schematically representation of the hydrogen preparation.    Device (1)    Hydrolysis reactor (3)    First inlet (5)    Second inlet (7)    Cooling unit (28)    Heat exchanger. (48)