Li+CO2- and Na+CO2- charge-transfer complexes were generated by cocondensation of alkali-metal atoms and CO2 molecules in argon matrices at similar to 4 K. The ESR spectra of Li+CO2- of both the C-s form and the cyclic C-2v form and Na+CO2- of the C-2v form were observed. The g-tensors, the C-13 hyperfine coupling tensors, and the alkali-metal atom hyperfine coupling tensors of the C-2v complexes were determined. The unpaired electron distribution (similar to 55% at C and similar to 35% at two oxygen atoms of the CO2 moiety and similar to 10% at the alkali-metal atom) determined from these hfc tensors is in good agreement with that given by the MNDO molecular orbital method. In the case of the Li/CO2/Ar system, a strong orientation effect was observed for the resulting Li+CO2- complexes. The orientation mechanism consistent with the observed effect is presented and demonstrated.