A cationic gold carbonyl complex has been synthesized and characterized using several techniques including X-ray crystallography. [(Mes(3)P)Au(CO)][SbF6] (Mes = 2,4,6-Me3C6H2) has a linear, two-coordinate gold atom. This compound displays the CO stretching frequency at 2185 cm(-1). The C-13 NMR signal of the gold-bound (CO)-C-13 appears as a doublet centered at delta 182.6 ((2)J(C,P) = 115 Hz). A computational study shows that the Au-CO bond consists of electrostatic attraction, Au <- CO donation, and significant Au -> CO pi-back-bonding components. Polarization of the CO bond caused by the electrostatic effect of the cationic gold center is mainly responsible for the large blue shift in the CO stretching frequency.