[en] Investigation of the NBI impact on the processes in tokamak plasmas requires detailed information about the distribution function of beam ions since it appears strongly anisotropic in velocity and inhomogeneous in spatial coordinates. Here we present the modelling results of distribution functions of energetic deuterons generated in ITER as a result of 1 MeV neutral beam injection. Considered are beam deuterons in energy range 100 keV < E < 1 MeV for basic ITER scenarios. The main attention is paid to steady-state distributions formed by steady NBI (at least over a 1 MeV deuteron slowing time), though for the prospect of gamma diagnostics of fast deuterons in ITER the temporal evolution of their distribution function after NBI switch-off is investigated as well. Calculations of steady-state beam deuteron distributions are performed using the 3D in constants-of-motion (COM) Fokker-Planck approach applied for interpretive modelling of beam ions in Trace Tritium Experiments (TTE) on JET, while the examination of the relaxation of the deuteron distribution is based on a time-dependent 3D COM Fokker-Planck code previously applied for analyzing the evolution of alpha particle induced gamma-emission in JET TTE. The thus modelled 3D COM distribution functions of beam deuterons are the founding element for simulations of poloidal profiles of beam deuteron density, of NBI power deposition to bulk plasma electrons and ions, as well as of the NBI generated current. In addition, the time evolution and the R, Z profiles of beam deuteron induced gamma-emission is modeled. Also the energy dependent neutral deuterium fluxes are calculated as induced by beam deuterons via various neutralization processes. Our modelling of NBI deuterons in ITER demonstrates the sensitivity of their distribution functions to different scenarios and proves the potential of gamma-diagnostics based on nuclear reactions of fast ions with Be and C impurities. Further validated is the capability of neutral particle diagnostics via analysis of energetic deuterium fluxes from ITER plasmas. (author)