AbstractIn this work, Raman spectra were taken continuously from CuSO4‐5H2O powders during a dehydration process at temperatures up to 400 °C. The spectra showed the variation in structures for both SO42and H2O. Furthermore, the band positions, band intensities, and their derivatives also showed these variations in structure and the amount of each component. From the intensities of the OH bands the amounts of water lost were found to be 2:2:1 in three stages as indicated by TGA/DTA. This method of monitoring variations in structure by Raman spectroscopy as a function of temperature can identify individual species and could be important to the study of a material's thermal properti