AbstractAcrylic resin/titania organic–inorganic hybrid materials were prepared by mixing titania sol produced by the sol–gel process with synthesized thermoplastic acrylic resins. The effects of the amounts of water and acid on hydrolysis and condensation of the sol–gel precursor (titanium n‐butoxide) were characterized by nuclear magnetic resonance, and their corresponding influences on the structure and properties of the hybrid films were investigated by small‐angle X‐ray scattering (SAXS), atomic force microscopy, dynamical mechanical analysis, an Instron testing machine, and ultraviolet–visible spectroscopy. SAXS indicated an open structure and nanoscale size for the titania phase of the hybrids. Higher titania content and a greater amount of water or acid in the sol–gel process resulted in titania domains that were larger size and had a more compact structure. The mechanical and UV‐shielding properties of the organic polymer obviously were improved with titania embedded. As the amount of water or acid in the sol–gel process increased, integrative mechanical properties decreased, with the amount of water having a greater impact than the amount of acid on the structure and optical properties. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3682–3694, 2004