A method for facilitating the impedance matching of radiofrequency circuits, notably transmission circuits using a power amplifier connected to a load which may include an antenna. A signal is produced for measuring the temperature resulting from the operation of the output amplifier stage, by a temperature sensor positioned in the immediate vicinity of this stage, the measuring signal is used to control a circuit for controlling the variable impedances of a matching network positioned between the amplifier and the load, and values which seek to minimize the sensed temperature are applied to these variable impedances values. An abnormal heating of the amplifier is an indication of an impedance mismatch that must be corrected to restore a minimum temperature.