The reactions of BrCH2CH2OH were investigated on clean and oxygen-precovered Cu(100) surfaces under ultrahigh vacuum conditions. Reflection-absorption infrared spectroscopy (RAIRS) studies were performed to examine the surface intermediates that were generated from BrCH2CH2OH decomposition. Density functional theory calculations were employed to predict the infrared spectra, assisting in the identification of the reaction intermediates. On Cu(100), -CH2CH2O-, formed from the simultaneous scission of the bromine-carbon and oxygen-hydrogen bonds of BrCH2CH2OH at similar to190 K, decomposed and evolved into C2H4 between 210 and 310 K in temperature-programmed reaction/desorption (TPR/D) experiments. A small amount of CH3CHO desorption was also observed. On oxygen-precovered Cu(100), -CH2CH2O-was also generated at lower exposures (<1.5 L) but at the BrCH2CH2OH dosing temperature of 115 K. The TPR/D study showed that C2H4 with minor amounts of CH3CHO evolved between 210 and 310 K. However, at higher BrCH2CH2OH exposures (greater than or equal to1.5 L), BrCH2CH2O-was the major intermediate formed at similar to200 K. The formation temperature of C2H4 and CH3CHO was extended to similar to400 K in this case.