We have investigated the effect of a Mo interlayer on the structural and electrical properties of Ni-silicided Si0.8Ge0.2 samples.. It is shown that the samples with the interlayers give lower sheet resistances than the samples without the interlayers when annealed at temperatures in the range of 450-800 degreesC. Glancing angle x-ray diffraction results show that regardless of the interlayers, only the Ni germanosilicide phase is formed across the whole temperature range. Scanning electron microscopy results show that the samples with the interlayers remain stable without serious surface degradation up to 600 degreesC. It is further shown that the samples without the interlayers experience abnormal oxidation at a fairly low temperature of 500 degreesC, while the interlayered samples remain stable without significant oxidation up to 800 degreesC. The Mo interlayer is found to move toward the surface region, when annealed at temperatures in excess of 450 degreesC. It is shown that the addition of the Mo interlayer effectively improves the thermal stability of the Ni-silicided Si0.8Ge0.2 layers. (C) 2004 American Vacuum Society.