This paper describes the application of a modern general purpose network analysis programme SPICE2 for the electrothermal analysis of hybrid integrated circuits. Self thermal coupling effects are modelled using the non-linear dependent current and voltage source capability in this programme, together with thermal environment parameters obtained from a three-dimensional thermal analysis program. Although numerical results are given by a bipolar transistor, the method is also applicable to monolithic integrated circuits and to resistors with variable temperature coefficients as power dissipating elements.