In This work, 6 to 11 mol% YO1.5-stabilized zirconia (YSZ) coatings were deposited by supersonic and conventional atmospheric plasma spraying. During spraying, the surface temperature and velocity of inflight particles were monitored by Spray Watch 2i on-line system. The phase composition of as-sprayed coatings was analyzed by X-ray diffractometry (XRD). Lattice parameters, tetragonality and the content of YO1.5 (mol%) of as-sprayed coatings were calculated according to the position of (004) and (400) diffraction peaks. It was found that the as-sprayed coatings were composed of metastable non-transformable tetragonal phase (t'). However, the amount of YO1.5 (mol%) in the as-sprayed coatings decreased with the increase of melting index of in-flight particles due to the partial evaporation of YO(1.5)during spraying. (C) 2013 Elsevier B.V. All rights reserved.