Binary chalcogenides with small Reststrahlen bands in the far infrared and microwave region make them intriguing for IR sensors and radar communication purposes. In this study, we have theoretically investigated the structural, phonon, electronic, optical, IR optical and thermodynamic properties of NpX, where X = S, Se, and Te chalcogenides. The face-centered cubic structure is relaxed to determine the optimized lattice parameters which increased with an increase in the size of involving chalcogen atom. Band structure reveals their metallic nature. The significant contribution of d and f-states of Np and p-states of chalcogens in band formation is evident from the density of state plots. The detailed analysis of optical parameters including real and imaginary parts of dielectric constant and refractive index, optical conductivity, and optical loss exhibit high absorption in the IR region.