The advanced internationalisation of markets and production processes continuously adds to the complexity of supply chains. At the same time improving the sustainability of the related international freight transport processes and optimising their efficiency is becoming a topic of central relevance. International freight transport models are an important tool to simulate impacts of measures taken to achieve such improvements of transport processes. Yet, the requirements towards international freight transport models are complex: they need to include various modes of transport, they need to cover different industries and their dynamics, they need to consider seasonality of supply and demand of goods, demographic parameters, economic developments, technological developments including their impact on production processes and structures, and many other aspects. Furthermore, international freight transport models need to include freight flows within countries as well as freight flows between the considered countries. This paper discusses the challenges which need to be confronted when developing international freight transport models which are able to correspond to the described complexity of international freight transport. Furthermore, it maps out the most important research gaps which need to be addressed by international freight transport modelling research in order to ensure that the challenges