Hydrogen passivation of acceptor dopants during metal‐organic chemical vapor deposition of GaN limits the acceptor concentration in as‐grown samples, and post‐growth annealing at ≥550 °C is necessary to reactivate the dopants. We have quantified the outdiffusion of hydrogen using 2H plasma‐treated (250 or 400 °C, 30 min) or 2H+‐implanted GaN, AlN, and InN annealed from 300 to 900 °C and used secondary ion mass spectrometry to measure the resultant distribution. In plasma‐treated GaN samples, two populations of 2H are found: (i) a high concentration (≳1020 cm−3), near‐surface (18 cm−3) plateau region extending throughout the film thickness (∼1 μm), most likely due to 2H‐point‐defect pairing. Deuterium in region (i) begins outdiffusion at 300 °C in GaN, but in region (ii) does not commence until ≳800 °C. In implanted samples the 2H redistribution occurs with the same characteristics as the bulk population in plasma‐treated material. The thermal stability of the deuterium profiles in all three nitride materials is much higher than that in GaAs and other compound semiconductors.