Prolonged photolysis of beta-[Mo8O26](4-) in the presence of electron-donative MeOH in aqueous solutions at pH 3.3 provides stepwise self-organization to paramagnetic reddish-brown mixed-valence species [(H14Mo24Mo13O112)-Mo-V-O-VI](12-). The X-ray structural analysis of the reddish brown crystals, isolated as [NMe4](+) alt, shows that [(H14Mo24Mo13O112)-Mo-V-O-VI](12-) anion consists of a central T-d [H-10((MO12O40)-O-V) ((MOO2)-O-VI)(3)](4-) core sandwiched by two [(H2Mo6Mo5O33)-Mo-V-O-VI](4-) ligands, with overall symmetry of D-2d The central {(Mo12O40)-O-V} subcore (with six short (MoV-MoV) contacts, 2.56(1) and 2.625(7)Angstrom) is a tetrahedral epsilon -Keggin structure with a cavity (in the size of similar to3.3 Angstrom) accommodating four protons and is stabilized by capture of four {(MoO2)-O-VI} groups with 3/4 occupancy. The {(Mo6Mo5O33)-Mo-V-O-VI}framework as the ligands consists of two sets of a dinuclear {(Mo2O4)-O-V} pair with a (MoMoV)-Mo-V . . . distance of 2.567(7) Angstrom, two sets of the edge-shared {(Mo2O10)-O-VI} octahedra, and three mononuclear groups of one (MoO)-O-VI and two (MoO2)-O-V. The MoV atoms in the two (MoO2)-O-V groups in the ligand are separated with a distance of 6.31(1) Angstrom, being ESR-active () = 1.909, g(perpendicular to) 1.894, and g(parallel to) = 1.939 at 77 K). The structure of the [(H14Mo24Mo13O114)-Mo-V-O-VI](12-) anion is slightly different from the diamagnetic species {[(H6Mo12O40)-O-V((MoO3)-O-V)(4)][(H3Mo4Mo6O29)-Mo-V-O-VI] [(H5Mo6Mo5O31)-Mo-V-O-VI]}(1 4-) prepared by thermal reduction of [Mo7O24](6-) with N2H4.H2SO4, in both structure and mixed-valency of the ligand. The stepwise self-assembly processes from beta-[Mo8O26](4-) to [(H14Mo24Mo13O114)-Mo-V-O-VI](12-) are discussed in terms of the photochemical multi- (six- and four-) electron reduction of beta-[Mo8O26](4-), which results in splitting into {Mo4}, {Mo-2}, and {Mo-1} frafments.