We propose to carry out μSR measurements of the BaFe2Se2O Mott insulator material in order to understand the nature of its magnetic order. Magnetisation measurements on single crystals displays three AFM transitions (at 240 K, 115 K and 43 K). Heat capacity and Raman scattering measurements suggest in addition short-range magnetic order that survives up to high temperatures. μSR is an ideal tool to study this material, as with a single technique we will have access to information on both the short and long-range magnetic order in the material. In order to gain understanding on this properties, we propose to carry out muSR measurements (in zero applied field and in an small longitudinal field applied in the direction of polarisation of the muons) as a function of temperature between 400 K and 10 K.