One of the most fundamental assets of natural polysaccharides is their water storage capacity. Analogically, materials able to regulate water hydration in energetic systems (e.x.: fuel-cells) are of paramount interest. In light of this key characteristic, chitosan, an aminocarbohydrate derived from shellfish waste, was structurally conjugated using sulfosuccinic acid to afford CS-SO3H. The resulting polymeric material appears well suitable for enhancing proton conduction and tuning the hydrophilic-hydrophobic balance of the proton exchange membranes (PEM). Consequently, Nafion membrane modified with CS-SO3H presented σH+ values almost 2 times higher than that of pristine Nafion at every % RH level exposed (30 °C - 80 °C and 30% - 90%). The σH+ enhancement is in agreement with the lower activation energy indicating that the proton transport is facilitated in the presence of -SO3H modified chitosan. We have found indications that –SO3H modified chitosan polymer, as a sustainable additive to Nafion is able to control the proton conduction mechanism and keep the activation energy for proton conduction at lower values as compared to pristine Nafion.