The invention relates to novel hydrates of dolutegravir sodium and to processes for their preparation. Furthermore, the invention relates to a novel crystalline form of dolutegravir sodium, which is a useful intermediate for the preparation of one of the novel hydrates. In addition, the invention relates to the use of the novel hydrates for the production of pharmaceutical compositions. Finally, the invention relates to pharmaceutical compositions comprising an effective amount of the novel hydrates and to the use of said pharmaceutical compositions in the treatment of retroviral infections such as HIV-1 infections.