AbstractThe recently proposed pseudo characteristic method of lines is applied to transient two -phase flow computations, A homogeneous equilib- rium flow model has been programmed for a single heated channel as a part of a code for transient analysis of pressurized water reactors based on the FORSIM simulation package, A variant including slip between the phases has also been tested. The conservation equation systems considered are hyperbolic and are written in characteristic form for a particular equation of state. lagrangian four-point upwind and upwind bias difference schemes as well as the Hermite 3,1 upwind formula have been used for equal spatial division. A standard flow-boiling problem and a reactor start up transient have been used to test the algorithm. The experience with different upwind discretization schemes and boundary approximations is discussed.