The effects of pre-oxidation of Incoloy 800H and Inconel 738 as a possible protective measure in reducing erosion-corrosion of the underlying alloy at temperatures up to 700°C have been investigated under conditions of moderate particle velocities and high particle loadings. This research also included assessment of the variation of erosion-corrosion with impact angle and alloy hot hardness. The results showed that the pre-formed scale exerted negligible effect on the erosion-corrosion of the substrate under these conditions. There were no significant differences between the wastage rates of the pre-oxidized and the as received alloys as the temperature was increased. The variation of erosion rate with impact angle followed the classical ductile mode at high temperatures. The reasons why pre- oxidation is ineffective under these conditions are discussed in terms of existing knowledge of erosion-corrosion in similar conditions.