Abstract: A fast response temperature probe which may be used for a method for measuring an instantaneous temperature of a periodically changing fluid flow within a gas turbine is proposed. The temperature probe includes a substrate and a resistive element arranged at a surface of the substrate. Therein, at least at a surface of the substrate contacting the resistive element, the substrate comprises an insulating material having a thermal product of less than 1.5 kJ/(m2K sqrt(s)). The substrate or at least its surface is made from polyamide-imide such as for example fiber-reinforced Torlon© 5030. The temperature probe may allow measurements of instantaneous local temperatures of very fast fluctuations of more than 50 kHz at high spatial resolutions of, e.g., less than 0.5 mm2. The instantaneous temperature of a periodically changing fluid flow may be determined by correlating first and second sets of temperature measurements taking into account the periodicity of the periodically changing fluid flow.