The utility of molten salts was demonstrated in the synthesis of the 1st family of mesoporous salt-inclusion solids featuring [V4O16] and [V5O17] polyoxovanadate (POV) units interlinked by As5+ cations, Cs3.5Na1.47(V5O9)(AsO4)2Cl2.33, Cs3.88Na0.12(V4.6O8.6)(AsO4)2Cl.99 and Cs3.64Na1.4(V4O8)(AsO4)2Cl3.04. Despite a high-temp. synthesis, these new solids exhibit unusually porous (∼2-nm-diam.) V arsenate frameworks. Disordered metal chloride salts reside inside the pores, leading to relatively large voids (up to ∼7.2% of the unit cell vol.), which were confirmed by surface area (SA) measurements of the as-prepd. polycryst. samples (∼90-110 m2/g). Given the potential utility of porous POV-contg. materials, efforts were made to study changes in the SAs (showing ∼35-70% increases) upon salt removal and redox chem.