Currently, the main energy options employed to maintain essential living standards, such as electricity, hot water and refrigeration, come from fossil fuels whose burning contributes to high environmental impacts like global warming. Then, the development of clean fuels is an important step towards sustainability. Hydrogen (H-2) can achieve such goal because its combustion mainly releases water. It can be obtained in different ways, including thermochemical cycles that consist of a sequence of chemical reactions to split water molecules into hydrogen and oxygen through a heat source at specific temperature conditions. Some traditional thermochemical processes available in the literature, like the cycles S-I (sulfur-iodine) and Cu-Cl (copper-chlorine) require temperature limits near to 900 degrees C and 550 degrees C, respectively. Additionally, the Mg-Cl (magnesium-chlorine) cycle can operate at temperatures about 450 degrees C while the U-Eu-Br (uranium-europium-bromium) cycle has its maximum operational temperature of 300 degrees C. In contrast to Cu-Cl, Mg-Cl and U-Eu-Br processes, which have relatively low and viable temperature ranges, there are thermochemical cycles that demand temperatures higher than 1000 degrees C. The low temperature requirement of a thermochemical process facilitates hydrogen production because it allows the use of many different heat sources like solar, nuclear and waste heat. In this line of reason, in a past work, it was proposed a new set of chemical reactions able to produce hydrogen, as a thermochemical process, which basic elements are sodium (Na), oxygen (O) and hydrogen (H). This system is named in this work as Na-O-H cycle and has potential to operate at temperatures about 400-500 degrees C or even below 400 degrees C. So, the aim of the paper is to present and evaluate a theoretical hydrogen production plant based on the Na-O-H cycle considering a Sodium Cooled Fast Reactor (SFR) as the heat source. The system was modeled in the Engineering Equation Solver (EES) software according to mass balances in addition to the first and second laws of thermodynamics. In this way, it was possible, for the first time, to estimate the amount of hydrogen obtained in this process. According to the results, the system can produce 1.321 kg/s of H-2, equivalent to 114 ton/day. This is a theoretical maximized value, because some aproximations were considered in the calculations. Additionally, the Na-O-H system has the potential for improvements through more research because it is in the initial stage of development. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.