Abstract Water activity measurements have been carried out on the aqueous solutions of both tri-potassium citrate (K3Cit) and polypropylene oxide (PPO) 400 +K3Cit over a range of temperatures at atmospheric pressure. The data obtained is used to calculate the vapor pressure as a function of temperature and concentration. The effect of temperature on the constant water activity lines of aqueous PPO +K3Cit systems has been studied and it was found that, at higher temperatures the higher concentration of polymer is in equilibrium with a certain concentration of the salt. Also it was found that the vapor pressure depression for an aqueous PPO +K3Cit system is more than the sum of those for the corresponding binary solutions. The experimental water activities have been correlated successfully with the segment-based local composition Wilson model. The agreement between the correlation and the experimental data is good.
