Titanium oxide (titania) nanoparticles (with a nominal size of about 10 nm) were synthesized directly from three organic precursors: titanium tetraisopropoxide (TTIP), and water-soluble titanium sources TC-300® and TC-400®, by using a low-pressure spray pyrolysis (LPSP) method. Effects of temperature, solvent, concentration and precursor type have been investigated systematically. We found that a higher temperature and a higher concentration were beneficial for the formation of nanoparticles. Addition of ethanol as a co-solvent improved breakup of droplets, and subsequently formation of nanoparticles. Water-soluble titanium sources showed great potentials for preparation of titania nanoparticles. The nominal size of nanoparticles calculated from electron microscopical images agreed well with that estimated from corresponding X-ray diffraction patterns, implying that nanoparticles were single crystals. The possible mechanism of particle formation in the LPSP process is also provided.