We have obtained accurate values for the electric quadrupole (Theta) and hexadecapole moment (Phi) of carbon dioxide. A very large (19s14p8d6f1g) basis set consisting of 456 uncontracted Gaussian-type functions is thought to provide near-Hartree-Fock values for both properties, Theta = -3.79ea(0)(2) and Phi= -1.41 ea(0)(-)(4) At the CCSD(T) level of theory a [8s5p4d2f] basis set yields (dTheta/dR)(e)= 1.26ea(0) and (d(2)Theta/dR(2))(e), = 2.7le, (dphi/dR)(e), = 24.5ea(0)(3) and (d(2)phi/dR(2)), = 76.6ea(0)(2) at the equilibrium bond length of R-e = 2.192 a(0). Our final estimate for the hexadecapole moment is phi(e) = -2.50+/-0.05ea(0)(.)(4) (C) 2004 Elsevier B.V. All rights reserved.