BACKGROUND: Bacterial cellulose (BC) synthesized by Acetobacter xylinum has been shown to be a potential matrix for impregnating carbon nanotubes (CNTs) to produce bacterial cellulose/carbon nanotubes (BC/CNTs) nanocomposite. The objective of this study was to investigate the crystal structure of BC/CNTs nanocomposite after acetylation treatment. Approximately 0.05 w/v% CNTs were added onto continuously developed BC. Then, the BC/CNTs nanocomposite was acetylated heterogeneously. RESULTS: The crystallinity characteristic of formed BC/CNTs acetate was analyzed using an X-ray diffractometer (XRD). The crystallization index (CrI) of BC/CNTs acetate was better than BC acetate, i.e. 97 : 3 and 93 : 7, respectively. The crystallite size of BC microfibrils in BC/CNTs sheet was reduced because of the impregnated CNTs. However, the reduction of crystallite size for BC/CNTs acetate was lower than that of BC acetate showing that the existence of CNTs within BC micofibrils had protected the BC crystal structure from further destruction by acetylating agent. CONCLUSION: CNTs is a powerful substance that acted as a void filler between BC crystalline structure and protected the nano-biocomposite from total degradation by the acetylation process. (C) 2011 Society of Chemical Industry