In this computational study, we investigated the degradation reactions at the interface between 2√3 x 4 surface cells of Ti 3 C 2 T x (T x = OH, O, Cl, F, and their mixture) and aqueous solution (Figure ), revealing sites that are the most prone for degradation reaction. (see SI for more details) To quantify the kinetic aspects of MXene stability in contact with water, we used AIMD simulations complemented with enhanced free energy sampling. These methods have been successfully used by us and others to study catalytic and degradation reaction mechanisms at solid-water interfaces. To evaluate activation energy associated with Ti atoms oxidation at MXene-water interfaces, we divided the trajectories obtained from the slowgrowth method into simulation windows separated by 0.1 Å and performed Blue-Moon sampling simulations, collecting energy gradients acting on Ti atom during at least 5 ps and further integrating the trajectory to get free energy surface. The distance between Ti and C atoms was chosen as a reaction coordinate, and the simulations were carried out until the gradients acting on Ti reached zero. As shown in Figure , the release of Ti from the subsurface to the MXene surface is followed by the attack of H 2 O molecule, leading to the stabilization of Ti-OH complex above the termination groups. We further calculated the activation energies (E A ) of the described reaction by integrating the energy gradients along the reaction coordinate. The process is possible to occur spontaneously at the O-terminated Ti 3 C 2 surface 36 due to a low E A of 0.28 eV, as shown in Figure . However, the release of the second Ti atom on the same surface was found to be much less favorable, with E A of 1.04 eV (see Figure ). This result is in qualitative agreement with recent simulations conducted for V 2 CO 2 . We attribute this behavior to changes in electrostatic potential associated with the formation of Ti(V)-OH dipole, as explained in more detail below. We further calculated E A for Ti sites at various Ti 3 C 2 T x surfaces, including O-, OH, F-and their mixed terminations (see Table ). Our simulations revealed that E A varies from 0.28 eV for the O-terminated surface to more than 3.9 eV for the OH-terminated surface, depending on the global composition of We first explored local properties associated with specific Ti sites at Ti 3 C 2 T x surfaces. Figure shows the correlation between the E A and d-band center of Ti site, which characterizes d-orbital occupancy and is commonly applied in predicting the reactivity of transition metals. We propose that the d-band implies a stronger bond, leading to higher E A values of reactions involving bond disruption. The positive correlation between activation energies and Ti vibration frequencies (Figure ) was found to be the strongest among the studied local descriptors. The lower frequency corresponds to softer out-of-plane Ti vibrations, leading to a less steep energy surface for Ti release. In this work, we used the vibration frequencies of Ti along the c-direction, which can be calculated by displacing single Ti atom and fixing the rest atoms in the unit cell as implemented in the finite differences approach. This method is very computationally efficient, while the calculated frequencies demonstrate good agreement with a more accurate projection of the phonon band on Ti atoms (Figure ). These findings highlight an important role of dynamic features, such as vibration frequencies and phonon modes, as promising descriptors associated with not only the conductivity of small ions, but also with surface reactivity and stability.