In this work, dehydration of Na3PO4. 12H(2)O has been studied dynamically in detail by thermo-Raman spectroscopy. The dehydration was observed in the temperature range from 30 to 200 degreesC. Spectral variation could distinguish six characteristic spectra of different hydrated species. The thermo-Raman intensity for the stretching bands of H2O showed four distinct steps of dehydration with Na3PO4. 12H(2)O, Na3PO4. 8H(2)O, Na3PO4. 7H(2)O, Na3PO4. 6H(2)O and Na3PO4.0.5H(2)O as the compositional species. The differential thermo-Raman intensity thermogram indicated the possibility of the existence of a new hydrated intermediate species Na3PO4.H2O during the dehydration. The first four steps of dehydration occurred below 84 degreesC and the last step of loosing 0.5 H2O could not be detected. The results of TG measurement showed only two stages of dehydration.