Among the factors influencing the adsorption activity of zeolites should give the number of cations in the zeolite, their availability for the adsorbate molecules and cationic charge density and radius of the cation. Synthesized samples of powdered zeolite LSX high phase purity and 100% crystallinity in NaK , Li, Na, K , Ca and Mg – forms. By X-ray analysis and the low-temperature nitrogen adsorption was studied the effect of the chemical nature of the cation exchange on the phase composition and characteristics of the porous structure of the zeolite LSX. The equilibrium adsorption capacity of the sample zeolite type LSX in NaK, Li, Na, K, Ca and Mg- forms of the water vapor. It has been shown that zeolite type LSX high degree of crystallinity and phase purity in Li- Na- forms can be synthesized starting from NaK- form, and K, Ca and Mg- forms – only from its Na- form. According to the low-temperature nitrogen adsorption determined that by replacing the cations NaK cations Li and Na, an increase, and when replacing the cations K, Ca and Mg – decreased availability of the crystal structure of the microporous zeolite LSX. Found that replacing cations can affect the limiting adsorptive capacity for water vapor ion-exchanged forms of zeolite LSX in the range of 0.27-0.34 cm3/g. Maximum values of the equilibrium water adsorption capacity are characteristic of zeolite LSX in Li- form.