We present magnetization and 77Se Nuclear Magnetic Resonance (NMR) measurements in single crystals of the magneteoelectric compound Cu2OSeO3. The temperature and field dependence of the magnetization suggest a ferrimagnetic ordering at Tc 60 K in a 3up-1down configuration. The easy axis of the magnetization is along the [100] crystallographic direction. The 77Se NMR line shape data collected at 14.09 T are consistent with the symmetries imposed by the cubic P213 space group in the temperature range 20–290 K and confirm that the magnetic transition is not accompanied by any lowering of the crystal symmetry as has recently been proposed by Bos et al. [Phys. Rev. B 78 094416 (2008)]. ; PUBLISHED ; One of the authors (H. B.) acknowledges financial support from the Swiss NSF and by the NCCR MaNEP