Wet chemical cleaning of the Si(100) surface is a critical step in wafer processing for microelelectronics. Oxidation of HF-etched (hydrogen-terminated) Si(100) surfaces occurs both intentionally (via peroxide solution) and uninentionally (e.g. during rinsing steps) and can affect both the chemistry and the morphology of the underlying substrate. We have used a combination of surface infrared spectroscopy and contact angle measurement to follow both the microscopic and macroscopic evolution of the H-terminated Si(100) surface during aqueous oxidation. Ex-situ transmission IR experiments allow us to elucidate the role of solution species including dissolved oxygen and OH@super -@ on both the rate and the mechanism of oxidation by following changes in both the Si-H and Si-O regions of the infrared spectrum. Contact angle hysteresis provides a measure of surface heterogeneity during these processes; comparison with the more uniform Si(111) surface provides a benchmark for the degree of inhomogeneity inherent to the rougher H:Si(100) substrate.