The critical properties and high-pressure binodal curves of binary mixtures of water + helium, neon, argon, krypton and xenon are discussed. The critical properties are compared with calculations using the van der Waals, Guggenheim and Heilig-Franck equations of state and the optimal values of the unlike molecular interaction parameters are determined. The agreement with experiment is very good. These interaction parameters are used in equation of state predictions of the binodal curves at various pressures between 50 and 250 MPa. The predicted binodal curves agree reasonably well with experimental data.