Two- and three-parameter Huckel equations have been determined for the mean activity coefficients of the electrolyte and for the osmotic coefficients of water in pure aqueous solutions of bromides and iodides of alkaline earth metals. The electrolyte parameters of the former equation are the ion-size parameter (B) and the hydration number parameter (b(1)), and they can be used at least up to an ionic strength (=I-m) of 2.0 mol.kg(-1). The latter equation is an extended Huckel equation, and it contains a quadratic term in the molality when compared to the usual Huckel equation. The coefficient of this term is parameter b(2), and this equation can be used in more concentrated solutions up to an I-m value of about 6 mol.kg(-1). All parameter values for the Huckel equations of MgBr2 and MgI2 were determined from the isopiestic data of Robinson and Stokes (Robinson, R. A.; Stokes, R. H. Trans. Faraday Soc. 1940, 36, 733-734). All parameters for the other alkaline earth bromides and iodides were obtained from other referenced sources (Robinson, R. A. Trans. Faraday Soc. 1941, 37, 82-84; 1942, 38, 445-446). These salts were measured in those studies against KCl solutions. In these estimations, the previously determined parameters for the Huckel and extended Huckel equations were used for the KCl solutions, see (Partanen, J. I.; Covington, A. K. J. Chem. Eng. Data 2009, 54, 208-219). The resulting parameter values were successfully tested with the cell potential, vapor pressure, and isopiestic data existing in the literature for solutions of these salts. Reliable activity and osmotic coefficients for alkaline earth bromide and iodide solutions can, therefore, be calculated by using the new Huckel equations, and these values are tabulated here at rounded molalities. The activity and osmotic coefficients obtained from these equations were compared to the values suggested by Robinson and Stokes (Electrolyte Solutions, 2nd ed.; Butterworths Scientific Publications: London, 1959, App. 8.10), to those calculated by using the Pitzer equations with the parameter values of Pitzer and Mayorga (Pitzer, K S.; Mayorga, G. J. Phys. Chem. 1973, 77, 2300-2308), and to those calculated by using the extended Huckel equations of Goldberg and Nuttall (Goldberg, R. N.; Nuttall, R. L. J. Phys. Chem. Ref Data 1978, 7, 263-310).