The electromotive forces E of the amalgam cells {LixHe1-x \ LiCl (m) \ AgCl \ Ag} and {LixHg1-x \ LiBr (m) \ AgBr \ Ag} have been measured as a function of the mole fraction x of Li metal in amalgams and of the molalities m of LiCl as well as LiBr at T = 298.15 K. For LiCl, the solvents investigated have been (acetonitrile + water), (1,4-dioxane + water), and (methanol + water) mixtures containing up to mass fi action 0.8 of the organic component, but only (acetonitrile + water) mixtures for LiBr. The standard molal electromotive forces E-m(0) have been determined and, for all the solvent systems explored, they appear to vary linearly with the mole fraction gamma of the organic component involved, according to the following equations: E-m(0)(LiCl)/V = 2.4169 - 0.2961 gamma(A); E-m(0)(LiCl)/V = 2.4175 - 0.5951 gamma(D); E-m(0)(LiCl)/V =2.4163 - 0.1749 gamma(M); E-m(0)(LiBr)/V = 2.2672-0.2092 gamma(A), where A denotes acetonitrile. D is 1.4-dioxane, and M is methanol. The relevant mean molal activity coefficients as functions of the LiCl and LiBr molalities have also been determined. The primary medium effects upon LiCl and LiBr, analysed in terms of the Feakins-French theory, lead to primary hydration numbers of approximate to 5 for LiCl and approximate to 4 for LiBr. These are somewhat lower than those obtained by other methods, but their difference is expected considering the known primary hydration numbers of the anions Cl- and Br-.