The coadsorption of CN- and CO on Pt(1 1 0) electrode in acid solutions was investigated by using cyclic voltammetry and in situ FTIR spectroscopy. In comparison with individual adsorption of CO or CN-, the onset oxidation potential of CO (COad) coadsorbed with CN- is positively shifted ca. 100 mV, and its oxidation peak is postponed ca. 260 mV together with a significant decrease in current density. When the coadsorbed CO has been stripped completely, the CV recovers the feature of Pt(1 1 0)/CN- surface, which signifies that the coadsorption of CO does not affect the oxidation behavior of the coadsorbed CN- (CNad-) comparison of CN- and CO adsorbed alone, the CNad- band is blue shifted from 2090 to 2108 cm(-1) at 0.0 V, and the stark tuning rate is decreased dramatically from 53 to 4 cm(-1) V-1; while the COad band is red shifted from 2075 to 2064 cm(-1) at 0.0 V, and the stark tuning rate is slightly decreased from 24 to 19 cm(-1) V-1. The result revealed the strong interaction between CNad- and COad at Pt(1 1 0) surface in the coadsorption system. (C) 2011 Elsevier B.V. All rights reserved.