The organic-inorganic hybrid crystal Ni(en)(3)Ag2I4 (where en represents 1,2-ethylenediamine) crystallizes in hexagonal space group P6(3), in which the AgI43- tetrahedra connect into a diamondlike inorganic framework via sharing of the vertex and the Ni(en)(3)(2+) octahedra fill in the pores of the framework. UV-vis-near-IR (NIR) spectroscopy disclosed that this hybrid shows intense NIR absorbance centered at ca. 870 nm, and the variable-temperature conductivity measurement revealed that the hybrid is a semiconductor with E-a = 0.46 eV. The electronic band structure of Ni(en)(3)Ag2I4 was calculated using the density functional theory method, indicating that the NIR absorbance arises from d-d transition within the Ni2+ cation of Ni(en)(3)(2+). The homogeneous, compact, and transparent crystalline film of Ni(en)(3)Ag2I4 was fabricated via a secondary seed growth strategy, which has promising application in NIR devices.