Strontium titanate (SrTiO3) nanotube arrays were produced through a simple hydrothermal process from amorphous TiO2 nanotubes arrays. The resulting samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). During the hydrothermal treatment, the TiO2 nanotube arrays retained their shape to produce SrTiO3 nanotube arrays. The formation mechanism can be explained by the nanoscale Kirkendall effect.