There is provided an adhesive comprising chitosan an optionally a crosslinking agent. A method for preparing such an adhesive is also disclosed. A wood-panel made with such an adhesive is also provided. Moreover, a method for manufacturing a wood-based panel is provided. The method comprises preparing a mixture comprising wood, chitosan, optionally a crosslinking agent, and optionally an acid, forming a mat with the mixture, and pressing the mat under heat and pressure so as to obtain the wood-based panel.