The aim of this work was to investigate the effects of chitosan oligosaccharides and chitosan on the rate of staling and properties of bread crumb and crust. Rates of crumb firming varied with storage time. The possible mechanisms including prevention of amylose–lipid complexation, acceleration of dehydration from both starch and gluten, adsorption of chitosan onto the starch surface and increase of moisture migration rate from crumb to crust are proposed and analysed. Chitosan oligosaccharides and low molecular weight chitosan increase bread crumb staling rate to a much lesser extent than does middle molecular weight chitosan.