Ab initio calculations of the O-17 electrical field gradient (EFG) tensor quadrupolar coupling constant (C-Q) and asymmetry parameter (eta(Q)), along with the O-17 NMR isotropic chemical shift (delta(iso)) for the three crystalline polymorphs Of P2O5 are presented. These computational results are compared with experimental values for crystalline h-P2O5 (hexagonal-form) obtained using a combination of solid-state O-17 magic angle spinning (MAS) NMR at three different magnetic field strengths (9.4, 14.1, and 19.6 T), two-dimensional (2D) multiple-quantum (MQ)MAS NMR, and 2D satellite-transition (ST)MAS NMR experiments. In addition ab initio studies of the model H4P2O7 cluster allowed empirical correlations between the bridging oxygen EFG parameters and the P-O-P bond angle to be developed.