Single crystals of Cs ₂(UO ₂)(CrO ₄) ₂ and Rb ₂(UO ₂)(CrO ₄) ₂ were prepared by solid state reactions. The structures are based upon the [(UO ₂)(CrO ₄) ₂] ^2- chains. Within the chains, UrO ₅ pentagonal bipyramids (Ur=uranyl) form Ur ₂O ₈ dimers, which are linked via CrO ₄ tetrahedra into one-dimensional chains. The CrO ₄ tetrahedra coordinate uranyl ions in both mono- and bidentate fashion, which is unusual for uranyl chromates. The bidentate coordination has a strong influence upon geometrical parameters of both U and Cr coordination polyhedra. The conformation of the chains in 1 and 2 is different due to the different size of the Cs and Rb cations.