Silicon samples of n-type have been implanted at room temperature with 5.6-MeV 28 Si ions to a dose of 2ϫ10 8 cm Ϫ2 and then annealed at temperatures from 100 to 380°C. Both isothermal and isochronal treatments were performed and the annealing kinetics of the prominent divacancy (V 2 ) and vacancy-oxygen ͑VO͒ centers were studied in detail using deep-level transient spectroscopy. The decrease of V 2 centers exhibits first-order kinetics in both Czochralski-grown ͑CZ͒ and float-zone ͑FZ͒ samples, and the data provide strong evidence for a process involving migration of V 2 and subsequent annihilation at trapping centers. The migration energy extracted for V 2 is ϳ1.3 eV and from the shape of the concentration versus depth profiles, an effective diffusion length р0.1 m is obtained. The VO center displays a more complex annealing behavior where interaction with mobile hydrogen ͑H͒ plays a key role through the formation of VOH and VOH 2 centers. Another contribution is migration of VO and trapping by interstitial oxygen atoms in the silicon lattice, giving rise to vacancy-dioxygen pairs. An activation energy of ϳ1.8 eV is deduced for the migration of VO, in close resemblance with results from previous studies using electron-irradiated samples. A model for the annealing of VO, involving only three reactions, is put forward and shown to yield a close quantitative agreement with the experimental data for both CZ and FZ samples over the whole temperature range studied.