Condition monitoring of power converters by way of sensorless temperature measurement is desired in order to optimize maintenance or increase performance. To date, there have been few investigations in this area for high-voltage IGBTs. This paper presents extensive measurements of temperature sensitive electrical parameters for a high-power 4.5 kV, 1.2 kA IGBT module. These parameters were extracted from switching transients in double pulse tests. The dependencies regarding collector current, collector-emitter voltage, and junction temperature were evaluated. Each parameter is rated regarding the suitability for online junction temperature estimation. The results showed that, since most parameters depend strongly on current and voltage in addition to temperature, the most suitable parameters were the quasi-static threshold voltage and maximum current and voltage rate of change during device turn-on.