The present work reports the measurement and mathematical correlation of phase equilibrium data for the binary system composed of carbon monoxide and water at temperatures up to 423.15 K and pressures up to 50 MPa. This data, although crucial when designing high pressure technologies, is not available in the literature. The experimental data were collected using a high pressure view cell. Mathematical correlation was performed using an online available programme tool Phase Equilibria (2000) with van der Waals cubic equation of state and a mixing rule proposed by Adachi and Sugie. The combination of EOS and mixing rule are found to be in good agreement with experimental data. (C) 2013 Elsevier Ltd. All rights reserved.