Experimental samples of mesoporous TiO2 with protonated and sodium-modified surfaces were obtained by sol-gel method. XRD, IR, X-ray fluorescence, and energy dispersive spectroscopy were used to characterize their crystalline structure, morphology and surface functional groups. The surface area of, and pore size distribution in the obtained samples were measured by the nitrogen adsorption/desorption isotherm, and calculated using the BET and non-local DFT theories. The adsorption of the Zn(II), Sr(II) and Ba(II) cations by the protonated and sodium-modified TiO2 surfaces was studied. The dependence of adsorption of the Zn(II), Sr(II) and Ba(II) cations on agitation time, solution acidity, and equilibrium concentrations of cations was investigated in a batch mode. It was shown that the kinetic model based on the pseudo-second order equation applied to the experimental results of adsorption of heavy metal cations by both adsorbents gives the highest coefficients of linear approximation (R2 = 0,99). Two most common adsorption theories, Langmuir and Freundlich, were used to analyze equilibrium adsorption data. Nonlinear approximation shows, that the Freundlich adsorption theory provides higher R2 and lower χ2, than Langmuir adsorption theory for adsorption of heavy metal cations by sodium-modified TiO2 surface. The maximum adsorption of the Zn(II), Sr(II) and Ba(II) cations by the sodium-modified TiO2 surface exceeds that of base sorbent with protonated surface by 2,27; 2,65 and 2,64 times, respectively. Experimental maximum adsorption values of Na-TiO2 toward zinc, strontium and barium cations are 93 mg·g−1; 208,4 mg·g−1, and 274,6 mg·g−1 respectively.Higher metal cations adsorption by Na-TiO2 is due to the Na+ cations, which released, through the ion exchange process. Sodium cations cause the dissociation of water molecules and local alkalization of the aqueous medium, which leads to the reduction of double-charged zinc, strontium and barium cations to single-charged ZnOH+, SrOH+ and BaOH+ cations respectively. Sodium-modified TiO2 involves only one ≡ТіОNa adsorption center in adsorption of the MeOH+ cation, while the protonated Н-ТіО2 sorbent spends two ≡ТіОНδ+ acid centers to bind the double-charged cation.