The microstructure and chemistry of TiN coatings on AISI 304 stainless steel:was characterized by a Zeiss EM 902A energy filtering transmission electron microscope (TEM) equipped with an electron energy loss spectroscopy (EELS) detector. Deposition of the TiN thin films was carried out by a hollow cathode discharge ion plating coater. The microstructure across the coating thickness direction and near the TiN/steel interfaces was investigated by plan-view TEM. It was found that the microstructure of the TiN coatings is thickness dependent. The grain size of TIN ranges from 88 nm at the coating surface down to 9 nm near the TiN/steel interface. In addition, the TIN surface layer shows slightly textured microstructure, but the subsurface and internal TIN layers have mainly equiaxial and randomly oriented microstructure. Chemical analysis of the coating and the interfacial region was done by EELS. It was obtained that the relative oxygen content increases linearly from the TiN surface to the TiN/steel interface, whereas the relative nitrogen content first decreases slowly and then drops rapidly near the interface. The presence of a Ti2N phase and the deficiency of nitrogen near the TiN/steel interface suggest that the early deposited TiN may be nonstoichiometry.