The system includes a reactor vessel having a reactor space bound by a reactor wall. The reactor vessel is arranged for holding a mixture of a catalyst and formic acid in the reactor space. The reactor vessel includes a mixture inflow opening for allowing the mixture to enter the reactor space and a mixture outflow opening for allowing said mixture to exit the reactor space, and a gas outflow opening for allowing hydrogen originating from the mixture to exit the reactor space. A method for hydrogen production includes providing the formic acid and the catalyst into the reactor space; withdrawing the mixture from the reactor space; heating and/or cooling the mixture to a predetermined temperature range outside the reactor space; and introducing the heated and/or cooled mixture into the reactor space in a predetermined direction having a tangential component arranged for stirring said mixture in the reactor space.