Abstract: AIMTo investigate whether tazobctam has crystallization water. METHODSIn order to establish a method for water content determination in tazobctam, many methods including Karl Fischer titration, weight loss on drying, TGA, DSC and X-ray diffraction experiment of an orthorhombic form were studied. RESULTSThe water content of the same batch tazobactam determined by different mthods was different. CONCLUSIONThe results showed that one mole tazobatam contains half mole water of crystallization and the strength of attraction between tazobatam molecule and water molecule is rather strong.