Copper, iron and zinc ions were added in liquid feedstock to deposit ion doped TiO₂ photocatalytic coatings through liquid flame spraying. The coating microstructure was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The photocatalytic performance of coatings was examined by photodegradation of acetaldehyde. XRD analysis showed that the crystalline structure of coatings was not significantly influenced by the metal ion doping. The photocatalytic activity of the TiO₂ coatings was enhanced by the metal ion doping at low dosage. High dosage of ion doping even decreases the activity. XPS analysis showed that the adsorbed oxygen concentration was increased with the increase of copper ion dosage and decreased with the further increase of ion dosage. This means that the enhancement of photocatalytic activity can be attributed to the adsorption ability of oxygen and other reactants on the surface of low concentration doped TiO₂ coatings.