<p>The effect of proton transfer in water has been studied by the molecular dynamics method with the ReaxFF potential, which supports the dynamic formation of bonds and makes it possible to simulate proton transfer. The self-diffusion coefficients of water and the diffusion coefficients of the H₃O⁺ and OH^– ions in the water have been studied along the water saturation curve from the triple to the critical point and in a wide pressure range from 1 to 300 MPa. A linear dependence of diffusion coefficients on temperature in Arrhenius coordinates has been obtained, and the transfer energies of molecules and ions have been examined.</p>