This article reports in situ FTIR monitoring of electrochemical reactions using a silicon-based thin-layer cell realized by micromachining fabrication technologies. ne proposed device contains a silicon micromachined cavity cell integrated with a gold working electrode, a counter electrode, and a Ag/AgCl reference electrode. Electrochemical, spectroscopic, and spectroelectrochemical characteristics of the fabricated cell have been experimentally measured and exhibited a comparable performance to commercialized CaF2 thin-layer cells. In situ spectroelectrochemical characteristics have been successfully tested for both 2 mM K3Fe(CN)(6) in an aqueous solution and 2 mM ferrocene in a dichloromethane solution using the fabricated thin-layer cell.