This publication provides a description of the Rossendorf coolant mixing (ROCOM) test facility, used to provide benchmark experiments related to the phenomena of pressurized thermal shock (PTS) and boron dilution, the calculation results using computational fluid dynamics (CFD) codes and methods, and the conclusions drawn from comparison of CFD results with experimental measurements. The aim of this benchmarking was to provide CFD practitioners with two high quality datasets of relevance to reactor transients inside a pressurized water reactor pressure vessel with different configurations and involving mixed convection, stratification, jet impingement and unsteady (inverse) plumes. The focus of the benchmarking was on the three main regions of the cold domain of the primary circuit, i.e. the cold leg, the downcomer and the core entry region. The work was carried out within the framework of an IAEA coordinated research project on application of computational fluid dynamics codes to nuclear power plant design.