Hydrogen-bonded assemblies of the two-electron reduced mixed-valence Keggin clusters [PMo12O40]5- and [SiMo 12O40]6- were obtained by the one-pot electron-transfer reactions between p-phenylenediamine (PPD) or 2,3,5,6-tetramethyl-PPD (TMPPD) (donors) and H+3[PMo 12O40]3- or H+4[SiMo 12O40]4- (acceptors) in CH3CN. The redox states of the [PMo12O40]5- and [SiMo 12O40]6- clusters were confirmed by the redox titrations and electronic absorption measurements. In (HPPD+) 3(H+)2[PMo12O40] 5-(CH3CN)3-6 (1), the N-H ∼ O hydrogen-bonded interactions between the monoprotonated HPPD+ (or diprotonated H2PPD2+) and the [PMo12O40] 5- resulted in a windmill-like assembly and hydrophilic one-dimensional channels are formed with a cross-sectional area of 0.065 nm 2, and these are filled by the CH3CN molecules. Also, the CH3CN molecules in salt 1 were removed by immersing the single crystals of 1 into H2O, CH3OH, and C2H 5OH solvents. In the compound, (HTMPPD+) 6[SiMo12O40]6-(CH 3CN)6 (2), the N-H ∼ O hydrogen-bonded interactions between the monoprotonated HTMPPD+ molecules and the [SiMo 12O40]6- formed a "Saturn-ring"-like assembly. Each Saturn-ring was arranged into an hexagonally packed array via hydrogen-bonded and π-stacking interactions of HTMPPD+, while the CH3CN solvent present in salt 2 are only found in the zero-dimensional isolated cavities.