The introduction of Eu2+ and Dy3+ co-doped SrAl2O4 phosphor as a bright long persistent phosphor (LPP) boosted the research in the field of LPPs. Soon, other members of the SrO-Al2O3 system attracted a lot of attention for different applications. Nevertheless, the applications are currently limited due to the large grain sizes of these materials. In this thesis, we present a novel method for the preparation of SrO-Al2O3 nanoparticles (NPs) in the range of 200-300 nm. CaO-Al2O3 NPs could be obtained with this method, as well. Luminescence properties of Eu3+-doped SrAl12O19 and CaAl12O19 nanocrystals were studied. Unlike the majority of Eu3+-based phosphors, in these NPs the strongest band originated from the 5D0→7F4 transition in the deep-red region of the spectrum. Emissions from the 5D1-3 states were also observed. Moreover, peculiarly strong 5D0→7F0 transition accompanied with a low-lying CT band was observed for Eu3+ in the amorphous phase of the SrO-Al2O3 NPs.