Based on the dividing surface concept and the Gibbs adsorption equation, a modeling approach was developed to accurately compute the surface tension of aqueous electrolyte solutions over a wide range of concentrations: from infinite dilution up to high molalities. A newly proposed thermodynamic expression based on the MSA, Born and Margules excess Gibbs energy equations was incorporated in this work to calculate the osmotic coefficients for the surface and bulk phases. The resulting model was successfully validated during the representation of the experimental surface tensions of various highly concentrated aqueous electrolytes solutions up to 36 molal at a single temperature (25 ºC). Model surface tension extrapolations at other temperatures were also verified.