Stationary two-phase flow experiments at pressures up to 13 MPa and temperatures up to 600 K have been performed in a converging nozzle. The experiment is specially designed for the assessment of two-phase computer codes used in reactor safety analysis, in particular for loss-of-coolant accident blowdown calculations. An assessment by the codes DUESE, DRIX-2D, and RELAP4/MOD6 is reported. The shape of the nozzle, the instrumentation, and the experimental program are such that models and empirical parameters of a wide range of codes can be tested and determined, respectively. Results show the influence and magnitude of models and parameter variations, the effect of the dimensionality and the difference scheme of the code, and the relevance of the models as a function of the initial conditions.