An acid-stable magnetic nanoparticle coated with silica bound to diglycolamide (MNCSDGA) has been synthesised and its sorption behavior for UO22+, Th4+ and Eu3+ from mediums containing high concentrations (0.5–6.0 M) of nitric acid (HNO3) was examined. Compared to other magnetic nanosorbents reported for UO22+, Th4+ and Eu3+ sorption from highly acidic mediums, MNCSDGA showed higher sorption capacities.