The stable water isotopes (H2O)-O-18 and HDO are incorporated as passive tracers into the oceanic general circulation model MPI-OM, and a control simulation under present-day climate conditions is analyzed in detail. Both delta O-18 and delta D distributions at the ocean surface and deep ocean are generally consistent with available observations on the large scale. The modelled delta D-delta O-18 relations in surface waters slightly deviates from the slope of the global meteoric water line in most basins, and a much steeper slope is detected in Arctic Oceans. The simulated deuterium excess of ocean surface waters shows small variations between 80 degrees S and 55 degrees N, and a strong decrease north of 55 degrees N. The model is also able to capture the quasi-linear relationship between delta O-18 and salinity S, as well as delta D and S, as seen in observational data. Both in the model results and observations, the surface delta-S relations show a steeper slope in extra-tropical regions than in tropical regions, which indicates relatively more addition of isotopically depleted water at high latitudes.