The structure of protiated, deuterated and composite cellulose hydrogels with plant cell wall (PCW) polysaccharides has been investigated by combined USANS/SANS experiments, complemented with spectroscopy and microscopy. The broad size range covered by the USANS/SANS experiments enabled the identification of cellulose architectural features in the cross-sectional and longitudinal directions. In the cross-sectional direction, cellulose ribbons are modelled as core-shell structures. Xyloglucan and mixed linkage glucans interfere with the cellulose crystallisation process, reducing the crystallinity and establishing cross-bridges between ribbons. However, only xyloglucan is able to establish strong interactions with the cellulose microfibrils, affecting the properties of the ribbons' core. Longitudinally, the ribbons are hypothesised to present a ca. 1.4-1.5 mu m periodic twist with a crystallite length of ca. 140-180 nm for the individual microfibrils. These results highlight the potential of USANS/SANS techniques to investigate the multi-scale architecture of cellulose hydrogels as well as the interaction mechanism between cellulose and PCW polysaccharides. (C) 2016 Elsevier Ltd. All rights reserved.