The authors have proposed a hydrogen concentration probe using catalytic reaction on Pt wire surface. To use this probe to detect a concentration change in a supersonic mixing layer, the response of the catalytic heat release rate must depend only on concentration change around the probe. Catalytic heat release rate on the Pt wire surface in unsteady state is measured using a constant temperature type hotwire anemometer technique and a shock tube to investigate the relation of the response of the catalytic heat release rate and Pt wire temperature. Catalytic heat release rate begins increasing at the arrival of the shock wave. The increasing rate of the catalytic heat release depends on the Pt wire temperature when the wire temperature is low. However, the dependence is very weak when the wire temperature is over about 680 K. This shows that not the catalytic reaction but molecular transfer from the flow to the Pt wire surface is the controlling step when Pt wire temperature is high enough. As a conclusion, the Pt wire temperature over about 680 K is necessary to use the hydrogen concentration probe in a supersonic mixing layer.