The crystal structure of (H(3)O)(2)Cr(4)O(13) is isotypic with K(2)Cr(4)O(13). The finite tetra-chromate anion in the title structure consists of four vertex-sharing CrO(4) tetra-hedra and exhibits a typical zigzag arrangement. The crystal packing is stabilized by hydrogen bonds between these anions and hydro-nium cations. The two different hydro-nium cations are surrounded by nine O atoms of tetra-chromate anions, with O⋯O distances ranging between 2.866 (8) and 3.282 (7) Å.