Epitaxial KTN (x = 0.35) thin films were prepared on (100) SrTiO3 substrates by the sol-gel process. In this paper, wide and narrow scans of XPS analysis were studied on the surface of the KTN thin films before and after Ar+ sputtering for 10 min. The results show that no impurity or residual carbon was observed in the films, except for some carbon contamination caused by handling and pumping oil on the surface of the films. The chemical composition of the films is in good agreement with the stoichiometry of the starting materials, as demonstrated by the ICP results. The valence states of the ions indicated that the films are KTN with a perovskite structure. XPS spectra of the films after Ar+ sputtering differ considerably from those of the as-grown films, which may be attributable to the preferred sputtering of potassium and to new valence states produced during the Ar+ bombardment. In addition, it was confirmed by the angle resolution XPS results that the chemical composition was well-distributed and that no other phase was observed apart from KTN in the near surface region of the films.