Titanium dioxide (TiO2) gel microspheres were successfully synthesized by sol-gel process in oil-in-water emulsion, and the effects of atoleine on the morphology and thermal behaviors of the microspheres were investigated. Atoleine has no obvious effect on the morphology of the TiO2 gel microspheres. The resulting particles show spherical structure and are suspended without coagulation. However, the additive atoleine changes the thermal behaviors of microspheres, and also alters the interior structures of the microspheres after non-equilibrium heat-treatment. The core-shell structure of microspheres begin to form at the temperature between 600 and 700 degrees C, which is attributed to the formation of rigid outer part from high crystalline and contraction of inner part in sequent calcination. The addition of 3 and 20 wt.% atoleine hinders the crystallization of the microspheres at the temperature of below 600 degrees C and leads to a solid structure instead of core-shell structure obtained with small amounts of additive atoleine (0 and 1 wt.%). (C) 2013 Elsevier B.V. All rights reserved.