A possibility to produce hydrogen without greenhouse gas emissions is to couple a thermochemical cycle with a nuclear reactor. Among the various thermochemical cycles, the Sulphur/Iodine process is currently the most studied. The production cost of hydrogen from this process is the sum of several cost accounts which are not at present known in any satisfactoryway. In this paper we present an approach to estimate the total production cost of 1kg of hydrogen. In order to overcome the problem of uncertain information associated with each cost account, we model them as fuzzy sets. We designed a software tool which enables us to easily define the necessary sets and computes reasonable results including the overall cost. Based on the assumed values given by recent research papers for the specific cost accounts, we were able to estimate the cost of being in the interval between 1.7 and 9.4e/kg, but most certainly between 3.0e/kg and 6.8e/kg.