Tertiary and secondary alcohols were directly reduced by saccharides, such as glucose, fructose, and cellulose, as well as by plant leaves and mushrooms in supercritical water using one-pot single-step reaction. Catalytic hydrogenations of olefins were also performed well in supercritical water in the presence of the saccharides. Nascent hydrogen can be an origin for both reactions because it is generated in supercritical water by the water-gas shift reaction of CO derived from aldehydes as decomposition products of the saccharides. Thus, bulk biomasses can be used as hydrogen donors in one-pot single-step direct organic transformations in supercritical water. (C) 2013 Elsevier B.V. All rights reserved.