Monodisperse porous SrTiO3 spheres with an average size of ca. 200 nm were synthesized via a hydrothermal route in the presence of poly vinyl alcohol (PVA). Characterization techniques such as X-ray diffraction, scanning electron microscopy, transmission electron microscopy, SAED, and high-resolution transmission electron microscopy were used to investigate the products. The results showed that these porous spheres were compared of small primary nanocrystals and pores were formed among them. The nanocrystal and pore diameters increased as the reaction time proceeded. It was suggested that the PVA played an important role in the mesoporous sphere's formation by means of preventing nanocrystal growth through a capping effect.