Hemicelluloses are among the most abundant natural polymers in the world and are consequently a potential source for sustainable materials, that has so far been underexploited. Galactoglucomannans are the principal hemicelluloses in softwoods and can be found in, for example, industrial wood processing waste-water. Currently, we are investigating the fractionation and purification of O-acetylgalactoglucomannans from newsprint and fiberboard mill waste-waters, as well as the preparation of new barrier films with low oxygen permeation and hydrogel materials from the fractions obtained. Self-supporting films have been formed by solution-casting. Interesting oxygen barrier and mechanical strength properties were achieved for films obtained from a physical blend of O-acetyl-galactoglucomannan and either alginate or carboxymethylcellulose. To create oxygen barrier films with high resistance towards moisture, benzylated derivatives of O-acetyl-galactoglucomannan were made. A hydrogel is a polymeric material that swells in water but does not dissolve, valuable for applications including drug delivery. In order to obtain the right properties, we performed tailored cross-linking to create a flexible network structure. The chemical modification procedure involves a methacrylation reaction carried out under mild conditions. Herein we review past work and present some new data on fractionation and purification of galactoglucomannans. © 2009 American Chemical Society.