The nuclear shielding for both the H-1 and F-19 nuclei of CH3F and CHF3 was investigated as a function of pressure and temperature. The density region investigated extended from low, gaslike conditions to study pairwise intermolecular interactions to high, liquidlike densities to study multibody effects on nuclear shielding. The temperature range was from 30 to 150 degreesC. Neat samples of CH3F and CHF3, along with CO2 mixtures of these fluorocarbons, were investigated by H-1 and F-19 high-pressure NMR. Molecular dynamics simulations were undertaken to describe the pair-distribution functions for both the neat samples and mixtures to aid in the interpretation of the H-1 and (1)9F nuclear shielding determined from high-pressure NMR. The NMR spectra of the neat fluorornethanes and their CO2 mixtures suggest that there are no distinct or specific interactions between the fluoromethanes and CO2 and that as the temperature increases the multibody effects play less of a role in nuclear shielding.