The vapour pressure of (sodium acetate + water) was measured in the temperature range 278.15 K to 308,15 K and in the molality range 0.65 mol . kg(-1) to 6.47 mol . kg(-1) with a static method. Water activities and osmotic coefficients were calculated. A comprehensive search of the available literature for the relevant thermodynamic data of the investigated system was carried out. The most reliable values were used in a least-squares treatment using the Pitzer formalism in the temperature range 255 K to 398 K and the molality range 0 mol . kg(-1) to 25 mol . kg(-1)