The present invention relates to a bio-based polyelectrolyte complex (PEC) composition suitable as a binder for fiber based materials, textiles, woven and nonwoven materials. The PEC composition comprises cationic biopolymer, anionic biopolymer acid and a polymer, and is further characterized in that the net charge of the PEC is cationic, the charge ratio of the anionic polymer and the cationic polymer is ≤1, the cationic biopolymer is chitosan, wherein the concentration of cation is 0.005-30%, the anionic biopolymer is polyanions derived from nature, the acid is a Brønsted acid and/or a Lewis acid, wherein the Brønsted acid is selected from any organic and/or inorganic acids, wherein the Lewis acid is selected from any cationic mono- or multivalent atom, the weight ratio between cation and anion is 1:0.1 to 1:20, the weight ratio between the cation and acid is 1:0.01 to 1:30, chitosan has a degree of deacetylation being 66-100%, and the pH is less than 7. The present invention further relates to a method for preparing the PEC composition, uses of the PEC composition, as well as method of treating materials with the PEC composition.