A method of simulating the dynamic behaviour of gas turbines based on the theory of one-dimensional flow is developed. The analysis results in two sets of spatial differential equations, containing independent functions defining the gas flow phenomena taking place in the engine, whose integration allows evaluation of the time derivatives of the engine rotor speeds. The technique allows the inclusion of such phenomena as compression and expansion, heat transfer, area change, separation and mixing of gas streams, friction, drag, and combustion occurring individually or simultaneously in the gas turbine model. The method is general, in that any gas turbine can be modelled provided its gas flow processes can be defined. The results of an application to an actual engine are given.