•An open benchmark based on the PERSEO data has been conducted in OECD/NEA/CSNI/WGAMA.•The paper summarizes PERSEO facility, selected test, benchmark targets and results.•Code modeling approaches of the benchmark participants are presented.•Qualitative and quantitative code accuracy has been evaluated.•Based on the benchmark results, possible future research activities are proposed. In the framework of the OECD/NEA/CSNI/WGAMA, an activity on the “Status report on thermal–hydraulic passive systems design and safety assessment” has been conducted. Within this activity, a benchmark exercise, based on the experimental data developed in the full scale PERSEO (in-Pool Energy Removal System for Emergency Operation) component separate effect test facility, built at SIET (Piacenza, Italy), has been proposed and carried out. An “OPEN” benchmark exercise, hosted by ENEA, has been conducted. Twelve results from eleven Organizations were submitted. PERSEO is a full-scale separate effect test facility designed to study a new passive decay heat removal system operating in natural circulation. Test 7 is a full pressure test (7 MPa) and investigates the system stability and the system operation. The accuracy of the calculated results has been evaluated both qualitatively and quantitatively. The latter has been conducted adopting the Fast Fourier Transform Based Method. The present paper summarizes the main features of the PERSEO facility and Test 7 and discusses the main results and outcome of the benchmark exercise.