System (I) for hydrogen production by dehydrogenation of formic acid (HCOOH), said system comprising: - a reactor vessel comprising a reactor space bound by a reactor wall , wherein said reactor vessel is arranged for holding a mixture of a catalyst and said formic acid in said reactor space , said reactor vessel further comprising a mixture inflow opening for allowing said mixture to enter, via said mixture inflow opening , said reactor space and a mixture outflow opening for allowing said mixture to exit, via said mixture outflow opening, said reactor space , and a gas outflow opening for allowing hydrogen originating from said mixture, via said gas outflow opening , to exit said reactor space ; - an inflow conduit , communicatively coupled for fluid flow, via said mixture inflow opening , to said reactor space , wherein said inflow conduit is arranged such that said mixture, in use, is introduced in said reactor space , via said mixture inflow opening , in a predetermined direction having a tangential component (T) arranged for stirring , in use, said mixture in said reactor space ; - a pump , communicatively coupled for fluid flow, via said mixture inflow opening and said mixture outflow opening , to said reactor space , wherein said pump is arranged for withdrawing, via said mixture outlet opening , said mixture from said reactor space and introducing, via said inflow conduit , said mixture into said reactor space ; - a temperature control arrangement , communicatively coupled for fluid flow to said pump , wherein said temperature control arrangement is arranged outside the reactor space for heating and/or cooling, in use, said mixture withdrawn from said reactor space to a predetermined temperature range before introducing, via said inflow conduit , said mixture into said reactor space . - a reactor vessel comprising a reactor space bound by a reactor wall , wherein said reactor vessel is arranged for holding a mixture of a catalyst and said formic acid in said reactor space , said reactor vessel further comprising a mixture inflow opening for allowing said mixture to enter, via said mixture inflow opening , said reactor space and a mixture outflow opening for allowing said mixture to exit, via said mixture outflow opening, said reactor space , and a gas outflow opening for allowing hydrogen originating from said mixture, via said gas outflow opening , to exit said reactor space ; - an inflow conduit , communicatively coupled for fluid flow, via said mixture inflow opening , to said reactor space , wherein said inflow conduit is arranged such that said mixture, in use, is introduced in said reactor space , via said mixture inflow opening , in a predetermined direction having a tangential component (T) arranged for stirring , in use, said mixture in said reactor space ; - a pump , communicatively coupled for fluid flow, via said mixture inflow opening and said mixture outflow opening , to said reactor space , wherein said pump is arranged for withdrawing, via said mixture outlet opening , said mixture from said reactor space and introducing, via said inflow conduit , said mixture into said reactor space ; - a temperature control arrangement , communicatively coupled for fluid flow to said pump , wherein said temperature control arrangement is arranged outside the reactor space for heating and/or cooling, in use, said mixture withdrawn from said reactor space to a predetermined temperature range before introducing, via said inflow conduit , said mixture into said reactor space . <EOS>