Hydrogen (or deuterium) incorporation in dilute nitride semiconductors modifies dramatically the electronic and structural properties of the crystal through the creation of nitrogen-hydrogen complexes. In this work, we investigate how the formation and dissociation of such complexes rule the diffusion of deuterium in GaAs 1− x N x. The concentration depth profile of deuterium is determined by secondary ion mass spectrometry under a wide range of experimental conditions that comprise different N concentrations (x= 0.09%, 0.40%, 0.70%, and 1.5%) and D irradiation temperatures (T D= 200, 250, 300 and 350 C). The experimental data are successfully reproduced by a diffusion model in the presence of strong D trapping. In particular, the deuterium diffusion and capture rate coefficients are determined, and a minimum decay length of the deuterium forefront is found at low T D (< 250 C) and high x (> 0.7%). These …