The application of thermal-hydraulic codes, mainly developed for LWR, for the design and safety assessment of Generation IV reactors, require an extended benchmarking activity in order to test their capability to correctly represent the physical phenomena characteristic of the new reactor systems. In the frame of the European FP7 GoFastR Project, ENEA has offered experimental tests related to the helium-cooled HEFUS3 facility (Brasimone in Italy) for the organization of a benchmark exercise aimed at the verification of T/H system codes. The test campaign includes seven steady-states at different operating conditions and two loss-of-flow accident (LOFA) scenarios to assess the numerical models in dynamic conditions. Seven organizations (ENEA, PSI, AEKI/CEA, KIT, NRG, RC-Rez) were involved in the benchmark exercise with six different codes (RELAP5, TRACE, CATHARE, SIM-GFR, SPECTRA and FLUENT). The present paper summarizes the outcome of the exercise. Considering some limits of the HEFUS3 experimental data, the analysis of the results has led to a general positive evaluation of the codes performance, allowing to draw recommendations for gas-cooled systems modelling and the needs for future code developments.