The refractive index of LiNiO 2 thin films is complex and exhibits both dielectric and metallic properties. With LiNiO 2 thin films coated on or inserted in photonic crystals (PCs), it is possible to enhance the absorptance in the designed (AB) n LiNiO 2 (BA) m PC structures. One-way absorption in the photonic bandgap of (AB) PCs has been observed via changing the optical transmitting direction. The positions, width, and strength of the absorption peaks depend on the thickness of the LiNiO 2 films, the incident angles, and the transverse electric/transverse magnetic modes. The photonic band structure can be employed to determine the allowed and forbidden photonic modes and the related optical properties for (AB) PC and (AB) n LiNiO 2 PCs. These novel absorption characteristics can enrich the optoelectric properties of LiNiO 2 thin films.