The adsorption process of water vapor on one strongly basic and two weakly basic macroreticular anion-exchange resins was examined by using a batch setting. Experiments were performed under a wide range of water activities (0.05-0.8) and at three different temperatures (298, 305, and 313 K). Applying Flory-Huggins theory, it was concluded that the strongly basic anion-exchange resin showed much stronger site binding of water molecules at low water activities than both weakly basic resins. No tendency of the adsorbed water to cluster could be observed for all three adsorbents in the activity range under study. Diffusion in the microparticles of the resins was found to be the rate-controlling transport process. The obtained effective intraparticle diffusivities were extremely small. An exponential decrease of the diffusion coefficients with increasing water concentration could be observed and was attributed to association of few water molecules in hydration shells around the functional units of the resins, hindering further solvent transport. Temperature change had no effect on the kinetics of the process.