for their discovery of hexenuronic acid in unbleached kraft pulp and for their development of a practical means for removing it. By removing the hexenuronic acid prior to bleaching reactions between it and the bleaching chemicals are avoided and hence the hexenuronic acid does not consume bleaching chemicals. This leads to less consumption of chemicals in the bleaching process and consequently to reduced costs. Furthermore, the pulp properties are improved, in particular its brightness stability. The method to remove hexenuronic acid developed by the laureates has been implemented in a number of commercial operations in countries including Finland, USA, Canada and Brazil.