Thermodynamic, economic and environmental impact assessments of a four-step Cu-Cl cycle developed for hydrogen production are performed using exergy, cost, exergoenvironmental and exergoeconomic analyses, and life cycle assessment. For the system considered under the baseline conditions, the total cost rate and environmental impact rate are determined to be 165 $/s and 37.6 Pt/s, respectively. The following Part II of this two companion papers leverages this paper's results to optimize the four-step Cu-Cl with respect to overall exergy efficiency, total cost rate and total environmental impact rate. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.