The structure and dynamics of physisorbed carbon dioxide on in situ cleaved single crystal sodium chloride surfaces was studied by means of elastic as well as inelastic helium atom scattering. At T-surface=80-83.5 K the diffraction patterns indicate a commensurate (2X1) monolayer superstructure on the (001) plane of the substrate, the unit cell containing a glide plane. This is in agreement with results obtained from low energy electron diffraction and infrared spectroscopy. In time-of-flight experiments single phonon low-energy loss and gain features were observed which can be attributed to acoustic and optical modes. Two higher-energy features are probably due to the first combination modes observed by helium atom scattering so far. The growth of solid CO2 adsorbed on NaCl(001) was also studied.