ABSTRACT Understanding the thermodynamic properties of steam at critical flow conditions is important to the design, operation and management of steam distribution network and hence the cost of production in steam-enhanced recovery projects. Using the homogeneous equilibrium model, the properties of steam at critical flow conditions are presented. These properties include critical velocity, critical pressure, critical temperature, critical steam quality, critical specific volume, critical steam flux and Napier's parameter. The critical velocity, Napier's parameter and the dimensionless form of other properties are shown to be functions of the stagnation steam quality. The steam pressure is shown to have a slight effect on some of the properties. Empirical correlations for these properties are established for selected operating ranges and experimental results are presented to verify the model's predictions.