Chitosan is an N-deacetylated derivative of chitin, a copolymer composed of 2-amino-2- deoxy-ẞ-D-glucose and N-acetyl glucosamine 8 units linked by ẞ(1-4) bonds (Figure 1a). As a potential papermaking additive, chitosan displays several advantages: has cationic charge and good film forming properties, presents structural an affinity for cellulose and can develop hydrogen bonding. The chitosan could be also environmentally attractive solution to synthetic polymers due to its biodegradability and biocompatibility." Furthermore, it displays 9,10 antibacterial and antifungal activity.11.12 These features are important for potential applications of chitosan as surface coating or wet end additive in the papermaking processes.