The invention relates to a method for the detection and/or measurement of fouling in a heat exchanger, whereby the resistance value (R1, R2) of a resistor (R), placed on a wall (P) of this heat exchanger, is measured at two different instants and a value of the measurements (R2; R1) that corresponds to a function of the values measured at these two instants is determined, characterized in that the resistor (R) is subjected in succession to two power levels (P1, P2) that are each maintained for a certain duration, the first power level (P1) being below the second power level (P2), and the measurements of the two resistance values (R1, R2) being respectively carried out during application of these two power levels. The invention also relates to a device for the detection and/or measurement of fouling in a heat exchanger, characterized in that it includes a resistor (R), placed on a wall (P) of this heat exchanger, means (16) for delivering a constant power to said resistor (R) and processing means (17), these various means being capable of implementing the method according to the invention Finally, the invention relates to the use of said method or of said device.