This study uses thermal conductivity and differential scanning calorimeter experiments to explore the thermal conductivity and phase-change properties of alumina (Al2O3)-water nanofluid produced using a two-step synthesis method. Deionized water (DW) is used as a control group, and the Al2O3-water nanofluid uses chitosan as a dispersant. Nanoparticle morphology and materials were confirmed using transmission electron microscopy (TEM) and X-ray diffraction (XRD), respectively. The results show that adding Al2O3 nanoparticles to DW improves DW thermal conductivity, but adding chitosan reduces the thermal conductivity of Al2O3-water nanofluid. Adding the nanoparticles to DW affects the phase-change peak temperature and phase change heat. The optimal combination is 0.1 wt.% chitosan and 0.5 wt.% Al2O3 nanoparticles; the charging phase-change peak temperature and latent heat are 53.4% and 97.8% of those in DW, respectively. (C) 2012 Elsevier Ltd. All rights reserved.