The results of an experimental investigation of the separation phenomena in dividing two-phase flow is presented. This work involved the commissioning of a steam-water loop to obtain detailed data on the characteristics of steam-water flow in a horizontal tee junction. Measurements included the pressure and void fraction distributions as well as the total flow rate and quality along the inlet and branching legs. A detailed set of experiments were performed enabling the effects of flow split, inlet quality and inlet mass flux on the separation and pressure characteristics to be determined. For the annular inlet flow conditions considered herein, total separation was approached when more than 40% of the inlet flow was removed through the branch. At lower branch flow rates, the degree of phase separation was strongly dependent on the branch flow split and the inlet quality. The pressure change from the inlet through the run of the tee was modelled from an axial momentum balance at the junction for both homogeneous and separated flow assumptions. The separated flow momentum correction factor was distributed about a value of unity indicating that the branching flow carriers little or no axial component of momentum. The pressure change from the inlet through the branch was considered in terms of reversible an'd irreversible components for separated and homogeneous flow assumptions. Both models yielded loss coefficients that were strongly dependent on the branch flow split and inlet quality. / Thesis / Master of Engineering (ME)