This work deals with physical properties of a fine capsulated latent heat storage material-water mixture. The fine capsulated material consists of pentadecane (C₁₅H₃₂, melting point of 283.1 K) as the core latent heat storage material and melamine resin as the coating material. The measured results of the physical properties of the test mixture, i. e., density, latent heat and viscosity, were analyzed for the temperature region of solid and liquid phases of the core latent heat storage material (pentadecane). It was clarified that the additional properties law could be applied to the estimation of density and latent heat of the fine capsulated latent heat storage material. Moreover it was found that the viscosity of the test mixture increased with an increase in concentration of the fine capsulated latent heat storage material. Useful correlation equations of viscosity for the fine capsulated latent heat storage material-water mixture were derived in terms of temperature and concentration.