We performed density functional theory based first-principles studies to examine the stability, electrochemical properties, and diffusion barriers of Ti 2 CSO and Ti 2 CSSe Janus MXenes for Li and Mg electrodes. We proved that both Janus structures are thermodynamically stable when Ti 2 C MXenes are functionalized with S and O/Se. The phonon calculations indicate that Ti 2 CST structures are dynamically stable at 0 K temperature. The elastic constants of both MXenes comply with the criteria for mechanical stability. The density of states plots of those Janus structures have metallic character while the region near the Fermi level is rich with Ti-d orbitals. This can offer good electronic conduction for the electrodes. The in-plain strain of the two Li/Mg layers adsorbed Ti 2 CSO MXenes is very small, while the out-of-plane strain is around 7 %. Ti 2 CSSe monolayers with two Li/Mg layers show strains between 2 % -4 %, whereas out-of-plane strain is less than 0.7 %. The ab initio MD calculations show that Ti 2 CSOLi 2 , Ti 2 CSOMg 2 and Ti 2 CSSeLi 2 structures are stable at 400 K temperature. The average voltage of Li adsorbed Janus MXenes are found as ≈ 0.95 V, and that of Mg adsorbed monolayers are ≈ 0.2 V. The theoretical capacities of the Janus MXenes are greater than 230 mAh/g, which is higher than the capacities of Li adsorbed M 2 CS 2 monolayers with M = Zr, Hf, V, Nb, Ta, Cr, Mo, and W. Ti 2 CSSe nanosheets show lower diffusion barrier compared to that of Ti 2 CSO MXenes. Ti 2 CSSeLi 0.0625 exhibits the lowest diffusion barrier (0.191 eV), which is lower than that of the 2D M 2 CS 2 electrodes, where M = Zr, Hf, V, Nb, Ta, Mo, and W.