Interstitial hydrides have a metallic bond. They are non stoichiometric which means the number of atoms of the elements presented cannot be represented by a ratio of small whole numbers and their composition varies with temperature and pressure$\mathrm{Z}\mathrm{n}{\mathrm{H}}_2$ is an example of interstitial hydride while $\mathrm{N}{\mathrm{H}}_3, \mathrm{C}{\mathrm{H}}_4\mathrm{ }\mathrm{a}\mathrm{n}\mathrm{d}\mathrm{ }{\mathrm{H}}_2\mathrm{O}$ are the examples of covalent hydride.