Itaconic acid is a naturally occurring dicarboxylic acid, produced by microorganisms through the fermentation of sugars, and has been named a great candidate for a future bio-based platform chemical. As it contains two carboxylic acid groups, alongside an unsaturation, several reactions may be performed to polymerize or conjugate the acid to bio-materials. In this study, itaconic acid and its anhydride are used to covalently bind to the pulp, that is bleached kraft pulp (BKP) cellulose fibres , through radical addition of the double bond, as well as esterification by utilizing the hydroxyl groups of the cellulose. The Itaconic-grafted pulp can then be further utilized for paper or board production with properties such as water retention or expressing higher wet strength. Esterification was performed in wet and dry conditions, through high-consistency mixing reactions and gas-phase reactions. Further, different cellulose sources, ranging from fibres to micro- and nanocrystalline cellulose   were used to screen the application of these reactions. The radical reactions were performed in water solution, with different quantities of persulfate acting as initiator. Additionally, the rate of addition of monomers or initiator, temperature and chemical environment were explored. The reaction outcome was verified using FTIR-ATR, polyelectrolyte titration, potentiometric titration, solid-state NMR, PXRD and water retention values.