We have synthesized mixed-valence derivatives of the layered oxide HLa Nb 2 O 7 , structurally related to perovskite, by chemical reduction, either at room temperature or at 650°C. The thermal behavior of this compound, its structure and change in transport properties upon high temperature doping are discussed. High temperature reduction turns the white insulating precursor into a mixed-valence blue bronze with a layered structure and semiconducting-like properties.