In this study, the phase transformation and the surface and interface morphologies of TiSi2 formed on atomically clean Si substrates are investigated. 200 angstroms Ti and 400 angstroms Si films on Si(111) have been co-deposited at elevated temperatures (400 °C-800 °C) in ultrahigh vacuum. The phase transition of TiSi2 is characterized with using XRD. The results distinguish the formation of the C49 and C54 crystalline titanium silicides. The surface and interface morphologies of titanium silicides have been examined with SEM and TEM. A relatively smooth surface is observed for the C49 phase while a rough surface and interface are observed for the C54 phase. The islanding of the C54 phase becomes severe at high temperature (800 °C). Islands of TiSi2 have been observed at temperatures above 700 °C but no islands are observed at temperatures below 600 °C. For films deposited at 400 °C and 500 °C, weak XRD peaks corresponding to TiSi were observed and TEM micrographs exhibited small crystalline regions of titanium silicide at the interface.