Cs2Pd3(P2O7)(2) (1) and Cs2Pd3(As2O7)(2) (2) have been synthesized by molten flux reactions and characterized by single-crystal X-ray diffraction. The structure of 1 consists of discrete (PdO4)-O-\\ squares which are linked by P2O7 groups via corner-sharing to generate a 3D framework containing 12-ring channels in which Cs+ cations are located. Compound 2 adopts a 2D layer structure with the interlayer space filled with Cs+ cations. Within a layer there are PdO4 squares and As2O7 groups fused together via corner-sharing. Adjacent layers are stacked such that strings of Pd atoms are formed. The PdO4 squares show eclipsed and staggered stacks with alternate short and long (PdPd)-Pd-... distances. The two compounds adopt considerably different structures although they have the same general formula: Cs2Pd3(X2O7)(2). Compound 2 is the first palladium arsenate reported. Crystal data for 1: orthorhombic, space group Cmc2(1) (No. 36), a = 7.6061(4) Angstrom, b = 14.2820(7) Angstrom, c = 14.1840(7) Angstrom, and Z = 4. Crystal data for 2: tetragonal, space group P4/n (No. 85), a = 16.251(1) Angstrom, c = 5.9681(5) Angstrom, and Z = 4.