This work is devoted to an \"old\" defect and its annealing characteristics, namely the divacancy center in Si. IR spectroscopy is applied to study the annealing kinetics of divacancy-related absorption peaks in electron-irradiated Czochralski-grown samples doped with B. In all specimens the kinetics show an exponential decay (first-order process) and a model taking into account both diffusion and dissocn. as annihilation mechanisms gives excellent quant. agreement with the exptl. results. Activation energy values extd. for diffusion and dissocn. are 1.28 eV and 1.71 eV, resp. In highly B-doped samples (0.1 Wcm), a strong dependence of the absorption bands on the Fermi-level position is obsd. during annealing .ltorsim.200 Deg and concurrently, a change of the divacancy charge state from neutral to singly pos. takes place. [on SciFinder (R)]