Niobium monoxide is the inorganic compound with the formula NbO.

It is a grey solid with metallic conductivity.

[1] NbO adopts an unusual cubic structure, similar to the rock salt structure but with some missing atoms compared to it, so that both niobium and oxygen atoms have square planar coordination geometries.

[2] One study of the bonding concludes that strong and nearly covalent bonds exist between the metal centers.

[4] It is a superconductor with a transition temperature of 1.38 K.[5] It is used in capacitors where a layer of Nb2O5 is formed around NbO grains as the dielectric.