Shuttle-like crystalline TiO₂ nanoparticles were synthesized by hydrolysis of titanium tetrabutoxide in the presence of acids in NP-5 (Igepal CO-520)–cyclohexane reverse micelle at room temperature. Pure rutile nanoparticles were obtained at appropriate acid concentrations. The influences of various reaction conditions, such as concentration and type of acid, water content, H₂O/Ti molar ratio, and reaction time, on the formation, crystal phase, morphology, and size of the TiO₂ particles were investigated.