Abstract Experimental setups and methods for obtaining Raman spectra at high pressure and high temperature are presented. Calibrations and technical improvements for increasing the pressure and temperature limits at which Raman spectra can be obtained reliably are discussed. Applications to determination of quasi-harmonic shifts are shown, with applications to thermodynamical modelling. Examples of the use of Raman shifts for calibration of pressure determinations in experimental setups and in natural rocks are described. Finally, the use of Raman spectroscopy in the study of in situ phase transitions at high pressure or high temperature is described using examples of first-order and higher-order transition in major Earth-forming minerals or analogues.