The initial switch in polycrystalline V2O5specimens (300–400 &mgr; thick) at room temperature is associated with melting caused by power‐induced Joule heating and also with a color change from yellow‐orange to black. The resulting black material exhibits threshold switching. High‐pressure studies show a pressure dependence on threshold power for V2O5, and on threshold field for an amorphous chalcogenide. Low‐temperature studies indicate an increase in turnover power with decreasing temperature for V2O5. High‐temperature studies show that V2O5melts with decreasing resistivity at about 690°C.