Abstract The adsorption of CO on Ni(111) in the low CO-coverage regime (θ CO ≲ 0.07 ML) has been investigated using FT-reflection absorption infrared spectroscopy. The FT-RAIRS results reported here provide a clear experimental evidence that at 85 K CO molecules occupy only the 3-fold bridge sites at low CO coverages. The population of the 2-fold bridge sites occurs only at higher CO coverages. In addition, the extended frequency range and the enhanced sensitivity of the FT-RAIR technique allows us to detect three types of 3-fold bridge v(CO) modes observed at 1815–1822, 1804–1808, and 1793–1799 cm -1, respectively. Possible origins of these v(CO) modes have also been postulated.