The work of Owen, Pincombe and Rogers (1985) makes use of integral momentum techniques to investigate the flow of an isothermal fluid in a rotating cavity with an imposed radial throughflow. This report extends the method by using an integral energy equation to predict the temperature in the core of the fluid when the discs of the cavity are heated, and have a given temperature distribution. The effect of various approximations are discussed, and the way in which the computed heat transfer depends on the mass-flow coefficient, the rotational Reynolds number and the type of disc-temperature distribution is found. Predictions using the theory are compared with the results of the experiments of Northrop (1984): good agreement is, in general, found.