Ammonium uranyl(2+) hydrogenselenate(1-) selenate(2-), (NH4)[UO2(HSeO3)(SeO3)], has a layered structure with only hydrogen bonding provided by the NH4+ ion and (probably) the protonated O atom of the hydrogenselenite ion connecting the layers, The U atom is surrounded by a pentagonal bipyramidal arrangement of O atoms.