Rapid relaxation of vibrationally excited carbon monoxide molecules by H2O and C2H2 has been studied by time-resolved Fourier transform infrared emission spectroscopy. The CO(upsilon) molecules were prepared by the laser-induced chemical reaction of CHBr3 with O-2. The temporal vibrational populations of CO(upsilon) are deduced from the time-resolved spectra. For H2O, eight relaxation rate constants of CO(upsilon = 1-8) are determined to be 1.7 +/- 0.1, 3.4 +/- 0.3, 6.2 +/-0.6, 8.0 +/- 1.0, 9.0 +/- 2.0, 12 +/- 3, 16 +/- 6, and 18 +/-10 (x10(-13) cm(3) molecule(-1) s(-1)), respectively. For C2H2, three rate constants of CO(upsilon = 1-3) are deduced to be 2.0 +/- 0.1, 6.0 +/- 0.5, and 9.4 +/- 2.0 (x10(-13) cm(3) molecule(-1) s(-1)), respectively. The excited CO(upsilon) molecules possibly transfer their vibrational energy to the nu(2) vibational modes of H2O or C2H2. The rapid relaxation of CO(upsilon) may be caused by many vibrational impacts in a transient hydrogen-bonded complex. Ab initio calulations are carried out for the CO-H2O and CO-C2H2 complexes. Theoretical calculations are also performed for the quenching rate constants based on both SSH theory and the V-V,R model.