Two types of rutile and anatase powders are used for the deposition of TiO2 coatings. The effects of plasma spraying conditions on the structure of TiO2 coatings are investigated in order to clarify controlling factors of the phase formation and to aim at the development of effective photo-catalyst TiO2. It is found that the amount of anatase TiO2 in the coating is influenced by spray parameters. The decrease of the heat input to spray droplet and an increase in the cooling speed during droplet deposition will increase the amount of the anatase TiO2 in the coating. As a photo-catalyst, the coating deposited under limited plasma power and by HVOF spraying using anatase powder is effective for the decomposition of acetaldehyde gas.