Ba8V7O22, the first vanadium oxide in which both VO-44 and VO8-6 coordinations and the coexistence and ordering of all the three common oxidation states of vanadium (+3, + 4, and +5) are observed, has been synthesized by reducing Ba2V2O7 in hydrogen at 1350°C. Single crystals of Ba8V7O22 have been grown by rapid cooling of its melt from ∼1530°C. Its crystal structure has been solved by single crystal X-ray diffraction, and magnetic and electrical properties have been examined. Ba8V7O22 crystallizes in the trigonal system, space group R3̄m (No. 166), with hexagonal lattice parameters a = 5.7841(7) Å, c = 57.074(11) Å, V = 1653.6(8) Å3, and Z = 3. The structure consists of face-shared VO8-6 and VO9-6 octahedra that form V3O14-12 trimers, corner-shared VO4-4 tetrahedra that are connected to the trimers such that they together form pseudo-two-dimensional magnetic layers perpendicular to the c-axis, and isolated VO3-4 tetrahedra that are arranged in planes separating the magnetic layers. It can also be described in terms of stacking of hexagonally close-packed Ba/O layers along the c-axis as a 24-layer structure with the stacking sequence of (hcc′hhc′ch)3, where h and c are hexagonal and cubic BaO3 layers, respectively, and c′ is a cubic BaO2 layer. Vanadium atoms occupy the tetrahedral sites and 34 of the octahedral sites in an ordered fashion. The 12-layer structure with (cchh)3 stacking, previously proposed for BaFeO3-x but improperly described in space group R 3m, is redescribed in R3̄m . The 24R structure of Ba8V7O22 is closely related to the 12R structure. Ba8V7O22 is a semiconductor with three activation energies ranging from 0.31 to 0.48 eV in the temperature range investigated (145-295 K), and a room temperature resistivity of about 12 Ω · cm. Its magnetic behavior is very complicated. Single crystal samples show a broad susceptibility maximum at 280 K, followed by an increasing susceptibility at lower temperatures and additional anomalies at 50 and 20 K.