Copper sulfide nanoparticles (Cu2-xS NPs) are p-type semiconductors that have the unique optical property of localized surface plasmon resonance (LSPR) in the near infrared (NIR). Therefore, they are expected to be useful for applications in various fields. However, the dispersion stability of nanoparticles, especially Cu2-xS NPs, is an important factor in their application. In the present work, we prepared pure CuS and polyvinylpyrrolidone (PVP)-coated CuS NPs and studied the effect of the dispersion stability on LSPR. Although pure CuS NPs are stabilized by the electrostatic repulsion of the citrate group in aqueous solutions, the NPs are aggregated, decreasing the intrinsic LSPR absorbance. Alternatively, PVP-coated CuS NPs show high dispersion stability due to the increased steric hindrance caused by the PVP polymer. To more accurately measure the dispersibility, a multiple light scattering technique is used to analyze both pure CuS and PVP-stabilized CuS NPs. The dispersion is also estimated numerically. Lastly, the superior energy conversion from NIR to thermal energy is verified by a thermographic camera. (c) 2017 Elsevier B.V. All rights reserved.