The life cycle analysis (LCA) is a versatile tool to evaluate process and production systems, and is useful to compare environmental burdens. For the purposes of this LCA, a high temperature electrolysis process was coupled to a high temperature gas nuclear reactor. The system function is the production of hydrogen using electricity and heat from nuclear power, with a functional unit of 1 kg of hydrogen, at the plant gate. The product system consists of the following steps: (i) the extraction and manufacturing of raw materials (upstream flows), (ii) the electrolytic cell fabrication, (iii) the nuclear fuel cycle, and, (iv) the hydrogen production plant. Particular attention was paid to those processes where there was limited information available on inventory data, for example mining and processing of rare earth metals, and electrolytic cell assembly, which are the primary components of a hydrogen generation plant. The environmental impact assessment focuses on the emissions of greenhouse gases (GHGs), as related to global warming. Additionally, other environmental loads, to complete the environmental profile of the product system, were included. The results were low GHGs emissions, with a value of 416 g of CO(2)eq kg(-1)H(2). As to the process components, the electrolytic cell showed the highest environmental impact. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.