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We produced gaseous hydrated clusters of sulfate and oxalate anions S[O.sub.4.sup.2-]-[([H.sub.2]O).sub.n] and [C.sub.2][O.sub.4.sup.2-][([H.sub.2]O).sub.n]], where n = 4 to 40]. Photoelectron spectra of these clusters revealed that the solute dianions were in the center of the water cluster, [([H.sub.2]O).sub.n]. For small clusters, these spectra were characteristic of the respective solutes, but beyond the first solvation shell (n ≅ 12), features in the spectra from the solutes were diminished and a new feature from ionization of water emerged, analogous to bulk aqueous solutions. For large dusters with dimensions greater than 1 nanometer, the solute photoemission features disappeared and the spectra were dominated by the ionization of water as the solvent coverage increased. A smooth transition from gas-phase clusters to behavior of electrolyte solutions was clearly revealed, and the large solvated clusters can be used as molecular models to investigate the photophysics and chemistry of aqueous electrolyte solutions., Cations often exhibit definitive solvation shells both in bulk aqueous solutions (1, 2) and in water clusters (3) because of their small sizes and strong solute-water interactions. However, the solvation [...]