Abstract Owing to the much concern with global environmental issues, Fe 3O 4 added photocatalytic TiO 2 coatings were deposited using plasma spray for environmental depollution. The influence of the content of Fe 3O 4 additive to the TiO 2 powder on the phase composition, microstructure and photo-absorption of plasma-sprayed TiO 2 coatings was systematically studied. The results showed that the TiO 2–Fe 3O 4 coatings consisted of anatase TiO 2, rutile TiO 2 and Fe 2TiO 5 pseudobrookite phase which appeared when the content of Fe 3O 4 additive was equal to or over 10%. The content of FeTiO 3 was highest in the sprayed TiO 2–10%Fe 3O 4 coatings. The addition of Fe 3O 4 improved the anatase–rutile transformation of TiO 2–Fe 3O 4 powders. Furthermore, it was found that TiO 2 coatings can decompose acetaldehyde under the illumination of ultraviolet rays, and the degrading efficiency was improved with an increase of FeTiO 3 content in the coatings. A two-step electron transfer model was proposed to explain the good photocatalytic activity of the sprayed coating with high content of FeTiO 3. However, presence of large amount of Fe 2TiO 5 compound substantially reduced the photocatalytic efficiency of the sprayed TiO 2–Fe 3O 4 coatings for its unfavorable photo-excited electron–hole transfer process.