The FEBEX (Full-scale Engineered Barriers Experiment in Crystalline Host Rock) ‘‘in situ’’ test was installed at the Grimsel TestSite underground laboratory (Switzerland) and is a near-to-real scale simulation of the Spanish reference concept of deep geologicalstorage in crystalline host rock. A modelling exercise, aimed at predicting field behaviour, was divided in three parts. In Part A,predictions for both the total water inflow to the tunnel as well as the water pressure changes induced by the boring of the tunnelwere required. In Part B, predictions for local field variables, such as temperature, relative humidity, stresses and displacements atselected points in the bentonite barrier, and global variables, such as the total input power to the heaters were required. In Part C,predictions for temperature, stresses, water pressures and displacements in selected points of the host rock were required. TenModelling Teams from Europe, North America and Japan were involved in the analysis of the test. Differences among approachesmay be found in the constitutive models used, in the simplifications made to the balance equations and in the geometric symmetriesconsidered. Several aspects are addressed in the paper: the basic THM physical phenomena which dominate the test response are discussed, a comparison of different modelling results with actual measurements is presented and a discussion is given to explain theperformance of the various predictions.