[ ] nanotubes for photocatalytic application have been synthesized by hydrothermal method. nanotubes are formed by washing process after reaction in alkalic solution. Nanotubes with different morphology have been fabricated by changing NaOH concentration, temperature and time. nanoparticles were treated inside NaOH aqueous solution in a Teflon vessel at for 20 h, after which they were washed with HCl aqueous solution and deionized water. Nanotube with the most perfect morphology was formed from 0.1 N HCl washing treatment. nanotube was also obtained when the precursor was washed with other washing solutions such as , NaCl, , and . Therefore, it was suggested that ion combined inside the precursor compound slowly comes out from the structure, leaving nanosheet morphology of compounds, which in turn become the nanotube in the presence of hydroxyl ion. To stabilize the sheet morphology, the different type of washing treatment solution might be considered such as amine class compounds.