Ion selective electrodes were used to measure the activity coefficients of individual chloride and bromide ions at 298.2 K in aqueous solutions of LiCl and LiBr up to 3 molal. The activity coefficients of lithium, calculated using values for the mean ionic activity coefficients are higher than those of potassium and sodium in the solutions with corresponding counterion. The results show that the activity coefficient of lithium is higher than the activity coefficient of the anion in the solutions of LiCl and LiBr. The chloride and bromide ions behave similarly with lithium or sodium as counterion. With potassium as counterion the activity coefficients of chloride and bromide are larger than with the other two cations. The Khoshkbarchi-Vera equation was used to correlate the experimental data. The results for the activity coefficient of individual ions in LiCl aqueous solution are compared with the values obtained from the hydration theory of Bates.