We present the deposition of amorphous Ti-Si-O thin films by an aerosol chemical vapor deposition process at atmospheric pressure. We used di-acetoxi-di-butoxisilane, tetrabutoxysilane, and titanium (IV) n-butoxide as precursors, and the deposition temperatures ranged from 475 to 675 degrees C. During the deposition process a chemical reaction between the different precursors took place. We found a synergetic mutual influence of the precursors and a coupled activation of the growth process between Ti and Si. The obtained thin films were characterized by various techniques: scanning electron microscopy, atomic force microscopy, X-ray diffraction, Raman spectroscopy, transmission electron microscopy, infrared spectroscopy, ellipsometry, and X-ray photoelectron spectroscopy. Our films were amorphous TiO2-SiO2 mixtures with a refractive index between 1.45 and 2.1 depending on the Si/Ti ratio in the films. We established a correlation between the X-ray photoelectron spectroscopy results and the refractive index of the films, allowing us to control the film composition as a function of the deposition conditions. (c) 2007 The Electrochemical Society.