In this paper we have demonstrated that Raman spectroscopy technique (using Raman peaks shift) is a suitable tool to assess the temperature of a thermal actuator in a MEMS device. The technique used is a spectrometric characterization that takes advantage of the Raman peaks shift caused by the increase in temperature. The method shows that it is possible to map areas with a resolution of a few microns and a temperature accuracy of the order of 0.01%/full scale. This technique lets good resolution and accuracy and allows several analyses: from simple thermal mapping to the system thermal physical parameters determination and the constant thermal resistance variation at micrometric scale.