Following the discovery of dye-sensitized solar cell, intensive research has been undertaken in developing semiconductor materials dyes, and the organic solvent or polymer electrolytes to enhance device performance. The sensitizer is typically regenerated by electron transfer from a donor, most commonly iodide ions that are dissolved in the liquid or semi-solid electrolyte present in the pores. The iodide is regenerated in turn by the reduction of triiodide at the counter-electrode. We propose here to utilize mixed-valent polynuclear electronically/ionically conducting inorganic materials, such as nickel(II) hexacyanoferrate(II,III) and Keggin-type heteropolytungstic acids (with and without triiodide/iodide redox couple immobilized in their secondary hydration spheres). The materials are characterized by fast dynamics of electron transfer between mixed-valent metal ion sites. Since the structures are hydrated, they are also good ionic (H+ or K+) conductors. Consequently, such redox - conducting materials have been successfully used by us as both electrolytes and charge mediators (relays) in dye-sensitized solar cells. The performance of devices has been evaluated on the basis of their photocurrent density-voltage characteristics and dark current measurements.