Na_xTi_nO_(2n+1) Whisker was prepared by Na^+/H^+ ion-exchange on layered hydrous titanium dioxide, H₂Ti₄O_9·nH₂O. The ion-exchange reaction proceeded at various mole concentration of NaOH solution that the host framework of [Ti₄O_9^(2-)]_n was remained unchanged. And the ion-exchange phase identified the phase transition through the heat treatment at various temperature. As the result of this experiment, NaHTi₄O_9·nH₂O was decomposed into Na₂Ti_6O_13 and TiO₂ in the temperature of 200℃∼600℃.