Novel metal oxynitrtides have been prepared by nitridation of amorphous metal oxide precursors obtained through citrate route. Their crystal structure, especially in O/N distribution and local bonding characteristics has been analyzed by using neutron diffraction, X-ray absorption and transmission electron microscopy, to investigate their electric and optical properties. In dielectric SrTaO₂N, crystal structure refinement suggested the short range O/N ordering and local tilting of cis-TaO₄N₂ octahedra, resulting in its unusual large permittivity. Its dense ceramics were sintered with SrCO₃ additive and exhibited superior dielectric constant above 1 × 10⁴ at room temperature. New biphasic wurtzite and zinc-blende structure of gallium oxynitride nanowire was observed by using transmission electron microscopy. As-grown long gallium oxynitride nanowire exhibited a characteristic broad UV emission at 4.3 eV in its cathodoluminescene spectrum. New oxynitride phosphor having magnetoplumbite structure, LaAl₁₂(O,N)₁₉:Eu showed photoluminescence emission peak splitting due to Eu²⁺ site splitting to two crystallographic sites induced by the two kinds of anions in its crystal structure.