This work presents a comprehensive study on the surface-property changes of 2D flakes of MXenes (Ti3C2 and Ti2C) upon interacting with the model cationic protein - lysozyme, using time-resolved dynamic light scattering and zeta potential. The study was also aimed at investigating how MXenes stoichiometry, structure, surface chemistry and exposure concentration effects its interactions with lysozyme. We found that the adsorption of lysozyme on 2D Ti2C and Ti3C2 flakes occurred effectively, leading to changes in MXenes zeta potential in a concentration-dependent manner. The lysozyme adsorption efficiency varied, depending on the surface chemistry and stoichiometry of the investigated MXenes. The results showed that the Ti3C2 MXene exhibited a higher adsorption of lysozyme in comparison to Ti2C MXene. The zeta potential assays revealed that the adsorption mechanism for MXenes was mainly electrostatic. We also demonstrated the lysozyme release from the MXene surface during pH changes to basic environment. Our findings highlight the importance of evaluating MXenes interactions with biomacromolecules and the mechanism for potential protein adsorption prior to designing e.g. drug delivery systems. We have shown that protein adsorption dramatically changes the surface-physicochemical properties of the MXenes, which may have a significant impact on the effectiveness and safety of future delivery, separation and purification systems dedicated to particular proteins.