The reaction of SO3 with either the palladium chlorides M2PdCl6 (M = Rb, NH4) or the nitrato-palladate (NO)(2)[Pd(NO3)(4)] at elevated temperature led to yellow single crystals of the complex palladates M-2[Pd(S4O13)(2)] (M = NH4: triclinic, P (1) over bar, a = 7.3882(3) angstrom, b = 8.5223(3) angstrom, c = 9.2712(4) angstrom, a = 71.945(2)degrees, beta = 88.910(2)degrees, gamma = 72.603(2)degrees, V = 527.88(4) angstrom(3); M = NO: triclinic, P (1) over bar, a = 7.2881(3) angstrom, b = 8.9125(2) angstrom, c = 8.9220(4) angstrom, a = 75.546(2)degrees, beta = 89.151(2)degrees, gamma = 69.516(2)degrees, V = 524.02(4) angstrom(3); M = Rb: triclinic, P (1) over bar, a = 7.4468(4) angstrom, b = 8.5066(4) angstrom, c = 9.2477(4) angstrom, a = 72.321(2)degrees, beta = 88.512(2)degrees, gamma = 72.128(2)degrees, V = 529.75(4) angstrom(3)). In the isotypic compounds, the Pd atom is in square planar oxygen coordination, achieved by two bidentate-chelating tetrasulfate anions. The reaction of Na2PdCl6 with neat SO3 afforded yellow crystals of Na2Pd(S4O13)(2) (monoclinic, P2(1)/c, a = 6.9953(4) angstrom, b = 15.9420(9) angstrom, c = 9.2299(5) angstrom, beta = 100.235(2)degrees, V = 1012.45(1) angstrom(3)). The structure exhibits no palladate complexes but an anionic two-dimensional network, according to (2)(infinity)[Pd(S4O13)(4/2)](2-). The latter shows the tetrasulfate anions acting as bidentatebridging ligands. The tetrasulfato-palladates were studied in more detail by means of thermal analyses and infrared (IR) spectroscopy. The observed IR bands were assigned according to quantum chemical calculations performed on the anion [Pd(S4O13)(2)](2-).