A nuclear based integrated system for hydrogen production and liquefaction with a newly developed four-step magnesium-chlorine cycle is proposed. The system uses nuclear energy to supply heat for the Rankine cycle and Mg-Cl cycle, where the power produced by the Rankine cycle is used to run the electrolysis steps of the Mg-Cl cycle and liquefaction cycle compressors. The four-step Mg-Cl cycle is specifically designed to decrease the electrical work consumption of the cycle by capturing HCl in dry form with an additional step to conventional three-step cycle. A performance assessment study is undertaken based on energy and exergy analysis of the subsystems, and total energy and exergy efficiencies of the plant are found to be 18.6%, and 31.35%. The comparisons of the subsystem efficiencies and total exergy destructions show that highest irreversibility ratio belongs to the Mg-Cl cycle by 41%, respectively. (C) 2016 Elsevier Ltd. All rights reserved.