Bacterial cellulose produced by Gluconacetobacter xylinus was treated with sodium carbonate (Na2CO3) and sodium hydroxide (NaOH) to remove entrapped noncellulosic materials. Fourier transform infrared (FTIR) spectroscopy has been used to investigate the effect of alkali on the chemical structure of bacterial cellulose. The changes in the crystalline nature of these membranes were analyzed using X-ray diffraction (XRD) technique. The morphology and the removal of noncellulosic impurities followed by alkali treatment were studied using scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS). The enhanced thermal stability of bacterial cellulose was evident from thermogravimetric analysis (TGA). Further, the alkali treatments resulted in relatively pure form of cellulose, which finds application in various spheres. (c) 2008 Wiley Periodicals, Inc.