The microwave spectrum of CO2-N2O has been obtained in the 7-19 GHz region using a Fourier transform microwave spectrometer. The nuclear quadrupole hyperfine structure in 26 a- and b-type rotational transitions has been analyzed using the Watson S-reduced Hamiltonian with the inclusion of nuclear quadrupole interactions. The rotational constants and six centrifugal distortion constants (in MHz) are A = 8843.4133(1), B = 1738.777 37(6), C = 1449.807 41(5), D-J = 6.510(3) x 10(-3), D-JK = -3.7405(8) x 10(-2), D-K = 2.3459(3) x 10(-1), d(1) = -1.3751(4) x 10(-3), d(2) = -8.3(1) x 10(-5), and H-J = -1.3(4) x 10(-7). The nuclear quadrupole coupling constants (in MHz) for the terminal nitrogen nucleus are chi(aa) = -0.0966(4), chi(bb) = -0.3111(4), and chi(cc) = 0.4077(4), and those for the central nitrogen nucleus are chi(aa) = -0.0411(6), chi(bb) = -0.0968(6), and chi(cc) = 0.1380(6). The spectroscopic constants are consistent with an approximately slipped parallel structure where the distance between the centers of mass of the subunits is 3.472 Angstrom, the acute angle between the CO2 molecular axis and the intermolecular axis is 62.8 degrees, and the acute angle between the N2O axis and the intermolecular axis is 58.1 degrees. The experimental data cannot identify whether the terminal nitrogen or the oxygen in N2O is closest to the C in CO2. The nuclear quadrupole coupling constants show that the electric field gradients at the nitrogen nuclei are perturbed to differing extents.