Infrared spectra of HCl-doped CO solutions have been studied at T similar to 140-90 K. First overtone and combination bands of the OC ... HCl complex were revealed at the lowest temperature of the liquid solution. Ab initio calculations utilizing the 6-311 + + G(3df,3pd) basis set with electron correlation at the nth-order Moller-Plesset (MPn, n less than or equal to 4) levels of approximation predict minima for the CO ... HCl and OC ... HCl linear structures. Based on simplified treatment of anharmonic interactions between CO and HCl constituents, the model estimations of the dipole transition moments have been performed.