We report a detailed study of the recombination processes of the excitons bound to O and Si shallow donors in bulk GaN. Photoluminescence (PL) and time-resolved PL measurement at different polarization and temperatures were carried out on a high quality 1-mm thick sample grown by Hydride Vapor Phase Epitaxy. Together with the principal donor-bound exciton (DBE) emission lines a large number of two-electron transitions (TETs) related to the ground and excited states of both DBE were observed allowing an accurate determination of the donor binding energies. Polarization properties and optical selection rules as well as the recombination dynamics of different PL lines were also studied and discussed. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)