The cloud-point (CP) temperatures and phase separation of {H2O + poly(ethylene glycol) + NaNO3} ternary system is studied by the turbidimetry method using a reaction calorimeter. The phase separation was also observed by visual inspection. Differences between the CP measured using the turbidimetry method and visual inspection, was up +/- 0.5 K. The Flory-Huggins model with a temperature and concentration-dependent interaction parameter was employed to correlate the phase diagram of the system. As a result of the correlation an average absolute deviation of 0.002 is obtained. (C) 2011 Elsevier Ltd. All rights reserved.