Three inorganic-organic-inorganic hybrids of dipalladium-substituted gamma-Keggin silicodecatungstates with organic linkers of different lengths, TBA(8)[{(gamma-H2SiW10O36Pd2)(O2C(CH2)(n)CO2)}(2)] (n = 1 (II), 3 (III), and 5 (IV), TBA = [(n-C4H9)(4)N](+)), were synthesized by exchange of the acetate ligands in TBA(4)[gamma-H2SiW10O36Pd2(OAc)(2)] (I-TBA) with malonic, glutaric, and pimelic acids, respectively. The X-ray crystallographic analysis of II, IIIA (IIIA: III with DCE, DCE = 1,2-dichloroethane), and IVA (IVA: IV with 10DCE) revealed that the anion parts of II, IIIA, and IVA were inorganic-organic-inorganic hybrids composed of two dipalladium-substituted gamma-Keggin silicodecatungstates connected by two dicarboxylate ligands. In the crystal structure of IVA, 10 DCE molecules per polyanion were present in the vicinity of polyanions. Compound IVB (IVB: IV with 0.2DCE) was obtained by the evacuation of IVA. The DCE sorption-desorption isotherms of IVB showed that the amount of DCE sorbed was saturated at 10.5 mol mol(-1), of which the amount was close to that (10 mol mol(-1)) of crystallographically assigned DCE molecules. In the DCE sorption-desorption isotherms, a low-pressure hysteresis was observed probably because of hydrogen-bonding interaction between DCE molecules and polyanions. The powder X-ray diffraction (XRD) pattern of IVA changed with decrease in the relative DCE vapor pressure to form IVC (IVC: IV with 0.7DCE) at P/P-0 = 0.0. The in situ powder XRD study showed reversible structure transformation between IVA and IVC driven by the sorption-desorption of DCE.