We present a first-principles computer simulation study of the sodium hydroxosodalite dihydrate Na-8[Al6Si6O24](OH)(2) . 2H(2)O. We have found that a fast proton exchange occurs, on the femtosecond scale, between two OH- encapsulated in the cavities (beta-cages) of the sodalite. The hosted species, formally two O2H3- groups not directly linked to the framework, show a correlation with the motion of the sodalite framework, indicating a nonthermal coupling between the zeolitic host and its molecular guests. The presented results are in agreement with experimental data.