${alpha}-Fe_{2}O_{3}$ films were prepared by ultrasonic spray pyrolysis (USP) on $SiO_{2}$ coated Si wafers using iron acetylacetonate as an iron precursor. The crystallographic properties and surface morphologies of the films were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. X-ray photoelectron spectroscopy (XPS) was carried out to determine the Fe oxidation states. In order to observe stability of the films to temperature, the resistance variation of the films with an ambient temperature was measured. The effects of substrate temperature on the structural and electrical properties of the ${alpha}-Fe_{2}O_{3}$ films were studied. The films were densified from the substrate temperature of $350^{circ}C$. The grain size of the films grown at $400^{circ}C$ was shown to be increased abruptly comparing with that of $350^{circ}C$. The films showed a low resistance variation between the ambient temperature of $300^{circ}C$ and $350^{circ}C$.