The implementation of a hydrogen transport economy based on renewable energy sources is seen by many as the ultimate sustainable transport solution. However, dimensioning of hydrogen production systems is complex: renewable energy sources are stochastic in nature, requiring the collection of empirical datasets relating to weather patterns on a daily, seasonal and annual basis; and hydrogen production is characterised by sensitivity to operating conditions and diversity in the performance of the component parts. A probabilistic model is developed for dimensioning of hydrogen production systems that removes the reliance on the collection of empirical datasets and the requirement for detailed performance characterisation of component parts. The model utilises well known correlations and distribution modelling techniques to predict energy output from either a photovoltaic array or wind turbine and hence the number of fuel cell electric vehicles (FCEVs) that could be supported on an annual basis. The model was implemented in MatLab and simulation results were compared with existing empirical based studies. Through simulation, limitations of the model were investigated and discussed. It was shown that the model was able to predict the number of FCEVs supported to within 10% (solar pathway) and 22% (wind pathway) for those studies investigated. These results are in alignment with the intention of the model as a first stage tool for the dimensioning of renewable hydrogen energy transport microeconomies. (C) 2013 Elsevier Ltd. All rights reserved.