A b s t r a c t The objective of this study is to develop a generic model for evaluating the potential demand for short sea shipping (SSS) in a given route. This model can be used in feasibility studies for novel SSS services, when shipping companies evaluate the potential demand for the service, considering the amount of cargo carried between regions and the potential for modal shift from road to sea. A model of costs and transit time across the entire supply chain is developed for unimodal and intermodal transport solutions based on cargo ro-ro ships. The model includes decision-making criteria on the preferable transport solution. The model is applied to the route between Leixões and Lisbon, for which the overall demand for cargo transport is obtained from statistical data relating to exports and imports split by NUTS 2 regions. 1 The model produces the amounts of cargo that could potentially be carried annually through each transport solution, for different freight rates and ship speeds, and allowing the identification of NUTS 2 regions for which the SSS solution is competitive. A sensitivity analysis is carried out to assess the effects of changes in several model parameters on results.