Single crystals of Magnéli phase V 9O 17 were successfully grown for the first time by a vapor transport technique utilizing TeCl 4 as a transport agent. No trace of syntactically intergrown V 8O 15 could be detected in these crystals. The structure is triclinic and is homologous to other Magnéli phase compounds V nO 2 n-1 ( n = 3 ∼ 8). The lattice parameters (of the reduced cell) measured are a = 7.009 Ȧ b = 14.518 Ȧ c = 5.418 Ȧ α = 95.5 ° β = 108.9 ° γ = 83.1 ° This compound manifests a metal-insulator transition as in other Magnéli phase compounds. The transition temperature has been determined to be 79 K. At and below the transition point down to 16 K, at which an anomalous peak in the resistivity exists, a time dependence of resistivity at fixed temperatures is found. The existence of V 10O 19 was also confirmed by transmission electron microscopy in a material produced under highly nonequilibrium conditions, intergrown in the matrix of V 9O 17 in a microsyntactoc fashion. The existence of V 10O 19 has never been reported.