Crosslinking of cellulose fibres was obtained by inducing a substitution reaction in a cationic cellulose ether (NMM-cellulose) prepared by action of N-oxiranylmethyl-N-methylmorpholinium chloride. During the reaction the N-methylmorpholine moiety of the cellulosic ether acts as a leaving group facilitating a covalent bond formation between the ether substituent and a hydroxyl or other nucleophilic group present in the cellulose chain. In order to provide additional evidence of the suggested crosslinking route and investigate its possibilities, different reaction conditions have been investigated and assessed in terms of the obtained fibre properties. The crosslinked fibres were characterized by means of elemental analysis and structure accessibility studies, including accessibility to water, anions and nitrogen gas. According to these investigations heating at 105 A degrees C induces a significant crosslinking. Pre-treatment with acetone restricts it mainly to formation of intra-fibre crosslinks, whereas heating from water suppresses the reactivity but results nevertheless in highly crosslinked structure with both intra- and inter-fibre crosslinks involved.