Magnetization measurements of Li2O crystals between 1.4 and 300 K reveal a diamagnetic-to-paramagnetic transformation of the samples, containing Li-colloids after electron irradiation near room temperature, and exhibit a break near 50 K as well as an antiferromagnetic ordering transition at 38 K. The magnetism is attributed to ⩽1% of molecular oxygen gas, freezing at 50 K, which is contained in micron-size cavities and produced simultaneously with the Li colloids. The earlier 7Li NMR experiments were extended to higher temperatures, in the range 300–520 K. The Knight-shifted Li-metal signal at ∼260 ppm is weakening during heating, due to annealing, but maintains its split double structure. The separation between the two peak components diminishes by ∼10%, after crossing the Li melting point at 453 K. The interpretation of these observations is discussed.