In this study, microstructure and electrical properties of Ag-TiO2 powders, which were prepared by a simple sol-gel method, are investigated. The sol was prepared from titanium iso-propoxide, Ti(OC3H7)4 in iso-propanol (CH3CHOHCH3), used as solvent. AgNO3 was used as the precursor for Ag. For the structural studies, the corresponding gels were allowed to dry naturally for about seven days, dried in an oven at 180• C for 30 min and then calcined at different temperatures (900, 1000 and 1100• C). The Ag-TiO2 nanoparticles were characterized using differential thermal analysis/thermal gravimetry, scanning electron microscopy, energy-dispersive X-ray analysis and X-ray diffraction. The results X-ray diffraction indicate that pure Ag and TiO2 powders are in rutile phase. However, calcination temperature had not significantly affected the crystalline structure of TiO2. Scanning electron microscopy images of powders show an aggregation of small spherical particles of dispersed sizes. Annealing of the Ag-TiO2 sample at high temperature produced more spherical particles, which aggregated to form bigger particles with porous structures. The electrical properties of the samples were measured using HMS-3000 Hall measurement system. The samples were found to be of n-type. IntroductionTitanium dioxide (TiO 2 ) has attracted interest due to such advantages, as effectiveness, chemical stability, nontoxicity, and relatively low cost, strong resistance to the chemical and photo-corrosion, low operational temperature, antibacterial properties and low energy consumption [1][2][3]. Titanium dioxide is one of the metal oxide semiconductors that have been widely examined for different purposes, since its physical and chemical properties show remarkable changes when the size of the TiO 2 approaches nm scale [4][5][6]. The modification of TiO 2 by means of metal doping can also affect the properties of TiO 2 . Silver, among the other metals, thanks to its high stability and excellent electrical and thermal conductivity, seems to be a favourable titania dopant [7,8]. In recent years, many researchers have investigated the effect of Ag nanoparticles on properties of TiO 2 [9][10][11][12][13][14][15]. Sol-gel is a low temperature, chemical solution method [16][17][18], which is a proven conventional method for preparation of composite Ag-TiO 2 compound.In this work, we have prepared nanosized TiO 2 and Ag-TiO 2 powders by sol-gel process, using titanium iso-propoxide and silver nitrate as precursors and isopropanol as solvent. The effects of Ag on the morphology, crystallization and phase transition of TiO 2 nanoparticles were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential thermal analysis (DTA) techniques.