[V4O8X(COO)4]z− or [V5O9X(COO)4]2− polyoxometallate anions can function as 4-connected nodes that assemble with 3-connected organic nodes (1,3,5-benzentricarboxylate) to afford small cubicuboctahedral hybrid nanoballs (hyball-3, -4, -5) in high yield. The resulting polyhedral cages exhibit 550 Å3 internal volumes and gas sorption measurements reveal that solid forms of the hyballs are permanently porous. The exterior surfaces of the hyballs are suited for further self-assembly and hyball-3 can serve as an octahedral supermolecular building block for the generation of primitive cubic (pcu) nets via two types of linkage: hydrogen bonds or coordination bonds.