The use of hot water immersion to aid in the drying of wafers subsequent to liquid chemical processing has recently been increasing. Both the TREBOR HydrodryTM and the Isopropyl Alcohol (IPA) dry used by CFM Technologies Inc. use water rinses at elevated temperature. These treatments are of particular concern when they follow HF immersions where surface oxides are removed and bare silicon surfaces are exposed to the hot water. Studies by Watanabe et al.1 show that Si(l 11) facets can be produced by hot water immersion. This, in turn, implies that hot water etches silicon with an anisotropic etch rate. In this work, the etching of oxide patterned Si(100) wafers by immersion in hot water is studied. Etching is clearly observed in images produced by Transmission Electron Microscopy (TEM) with a concomitant increase in surface roughness. The rate of etching varies dramatically with the dissolved oxygen concentration of the water used. Possible mechanisms to explain the etching will be discussed.