The Huckel equation used in this study to correlate the experimental activities of dilute solutions of silver nitrate, alkali metal fluorides, and sodium and potassium salts with dihydrogen phosphate, dihydrogen arsenate, and thiocyanate ions up to a molality of about 1.5 mol kg(-1) contains two parameters being dependent on the electrolyte: B [that is related closely to the ion-size parameter (a*) in the Debye-Huckel equation] and b(1) (this parameter is the coefficient of the linear term with respect to the molality, and this coefficient is related to hydration numbers of the ions of the electrolyte). In more concentrated solutions of these electrolytes and of alkali metal nitrites in the best case up to a molality of 10 mol kg-1, an extended Huckel equation was used; it contains additionally a quadratic term with respect to the molality, and the coefficient of this term is the parameter b(2). All parameter values for the Huckel equations of AgNO3 solutions were determined from the isopiestic data measured by Robinson and Tait for solutions of this salt against KCl solutions (Trans. Faraday Soc. 1941, 37, 569-570). All Huckel parameters for NaSCN and KSCN, those for NaF and KF, and those for RbF and CsF solutions were determined from the isopiestic data of Robinson (J. Am. Chem. Soc. 1940, 62, 3131-3132), Robinson (J. Am. Chem. Soc. 1941, 63, 628-629), and Ti Tien (J. Phys. Chem. 1963, 67, 532-533), respectively, where these salt solutions were measured against KCl solutions. All Hiickel parameters for KH2PO4, KH2AsO4, and NaH2AsO4 solutions were determined from the data of Scatchard and Breckenridge (J. Phys. Chem. 1954, 58, 596-602) where these salts were measured against NaCl. Also the parameters for the Hiickel equation of NaH2PO4 were determined from these data, but the parameters of the extended Huckel equation for this salt were obtained from the data of Stokes (Trans. Faraday Soc. 1945, 41, 685-688) against KCl. The Hiickel parameters for concentrated NaNO2 and KNO2 solutions and for concentrated LiNO2, RbNO2, and CsNO2 solutions were determined from the osmotic coefficients reported by Chekhunova and Protsenko (Russ. J. Phys. Chem. 1967, 41, 1220-1221) and by Chekhunova et al. (Russ. J. Phys. Chem. 1969, 43, 1158-1161), respectively. The osmotic coefficients for nitrite solutions were based on direct vapor pressure measurements. In the estimations from the isopiestic data, the Hiickel parameters determined recently for NaCl and KCl solutions (J. Chem. Eng. Data 2009, 54, 208-219) were used. The resulting parameter values were tested with the vapor pressure and isopiestic data existing in the literature for the solutions of these salts. Most of these data support well the recommended Hiickel parameters at least up to a molality of 3.0 mol.kg(-1) for all salt solutions considered. Reliable activity and osmotic coefficients for solutions of these electrolytes can, therefore, be calculated by using the new Hiickel equations, and they have been tabulated 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), to those calculated by using the Pitzer equations (Activity Coefficients in Electrolyte Solutions, 2nd ed. ; CRC Press: Boca Raton, 2000; pp 100-101), and to those calculated by usng the extended Hiickel equations of Hamer and Wu (J. Phys. Chem. Ref Data 1972, 1, 1047 - 1099). The recommended values for alkali metal nitrites were compared to those obtained by the extended Hiickel equations of Staples (J. Phys. Chem. Ref Data 1981, 10, 765-777).