This paper describes the application of high resolution pyrometry for surface temperature measurements of the blading in heavy duty gas turbines. First of all, it is essential to know the actual loading, since the cylindrical pyrometer probes are traversed into the hot gas path. Therefore, analytical methods for the calculation of the heat transfer, equivalent stresses and natural frequencies of the probes are described here. The second part presents results of measurements from the latest model V84.3A 60Hz 180 MW gas turbine in the Berlin full load test bed. Emphasis is put on the effect of combustor radiation, limited resolution of the pyrometer and 3D presentations of the data.