The degradation of docetaxel drug substance and its injection formulation has been investigated. The majority of impurities were observed in a base degradation study and all five degradation products were characterized. These impurities were isolated, enriched and were subjected to mass and NMR spectral studies. Based on the spectral data, these were characterized as 10-deacetyl baccatin III, 7-epi-10-deacetyl baccatin III, 7-epi-10-oxo-10-deacetyl baccatin III, 7-epi docetaxel and 7-epi-10-oxo-docetaxel, respectively. The last two impurities were also detected in the stability study of docetaxel formulation. Out of these degradation impurities two substances have been previously identified while the other three previously unreported.