As a breakthrough to the traditional 1H diffusometry, the interaction of cations with cellulose is investigated via7Li and 23Na PFG-SE NMR. The diffusion coefficient of Li+ decreases more than that of Na+ with the addition of cellulose, which indicates a stronger binding of LiOH with the macromolecule. Therefore, a new, facile, accurate and repeatable method to characterize ion/polymer interactions is established.