A novel surface modification method for titania nanoparticles is provided via the surface-initiated photocatalytic polymerization with the aid of acrylic acid (AA) or sodium styrene sulfonate (NaSS). The properties of modified titania nanoparticles are investigated with aqueous electrophoresis measurements, dynamic light scattering (DLS), and transmission electron microscopy (TEM). Then the modified titania is used as Pickering stabilizer for further polymerization and the morphology of the resulted polymer microspheres is characterized by TEM and field-emission scanning electron microscopy. It is proven that the addition of AA or NaSS for the surface-initiated polymerization can obviously affect the structure and morphology of the final polymer composite microspheres. The formation mechanism of several kinds of polymer particles is also proposed. (C) 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem49: 5257-5269, 2011