In this study we developed new thermodynamic models for solution behavior and solid-liquid equilibrium in eight acetate binary systems from low to very high concentration at 25oC: six systems of the type 1-1 (X(CH3COO)-H2O with X= (Li, Na, K, Rb, Cs, and Tl)) and two systems of the type 2-1 (Y(CH3COO)2-H2O with Y= (Mg, and Ba)). Models were developed on the basis of Pitzer ion interactions approach. To parameterize models for binary systems we used all available experimental osmotic coefficients data (φ) for the whole concentration range of solutions. To develop models, we used different versions of the standard molality-based Pitzer approach. It was established that for all acetate systems under study application of extended approach with 4 parameters (β0 , β1 , β2 and Cφ ) and variation of 1 and 2 terms in fundamental Pitzer equations leads to the lowest values of standard model-experiment deviation. The predictions of new developed here models are in excellent agreement with experimental φ data, and with recommendations on the mean activity coefficients (±) from low to very high concentration: up to 23.8 m in K(CH3COO)-H2O, up to 39.2 m in Rb(CH3COO)-H2O, and up to 52.2 m in Cs(CH3COO)-H2O. On the basis of evaluated binary parameters important thermodynamic characteristics (Deliquescence Relative Humidity DRH, thermodynamic solubility products Ko sp; standard molar Gibbs free energy of formation, fGo m) for 7 acetate solids were determined at 25oC. The calculated DRH and fGo m values were compared with those reported in the literature. The models described in this study are of high importance, especially in development and improvement of technology for production and purification of acetate solutions and solid phases.