In this work we present a study of the magnetic and transport properties of the system ${\mathrm{LaNiO}}_{3\mathrm{-}\mathit{x}}$ (0⩽x⩽0.5) where the x=0 member is a well-known metallic oxide. We found that the x=0.5 compound is an antiferromagnetic insulator at room temperature. The metal-insulator transition is observed for an x value around x⩾0.25. The role played by the sample inhomogeneities on the occurrence of this transition is discussed. © 1996 The American Physical Society.