(1) Department of Soil Physics and Chair of Geomorphology, University of Bayreuth, Universitätsstr. 30, 95440 Bayreuth, Germany, 2) Department of Terrestrial Biogeochemistry, Martin-Luther University Halle-Wittenberg, Weidenplan 14, 06120 Halle, Germany, 3) Institute of Plant, Animal and Agroecosystem Sciences, ETH Zurich, Universitätsstr. 2, 8092 Zurich, Switzerland, 4) Thermo Fisher Scientific, Hanna-Kunath-Str. 11, 28199 Bremen, Germany, 5) Earth Surface Science, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Sciencepark 904, 1098 XH Amsterdam, The Netherlands Organic Geochemistry (2012), V42, pp1470–1475, doi: Absence of oxygen isotope fractionation/exchange of (hemi-) cellulose derived sugars during litter decomposition Michael Zech (1,2), Roland A. Werner (3), Dieter Juchelka (4), Karsten Kalbitz (5), Björn Buggle (1,2) and Bruno Glaser (2) Aiming at developing a novel tool for palaeoclimate research, we recently proposed a new method for determining the oxygen isotope composition of monosaccharides (Zech, M., Glaser, B., 2009. Compound-specific d18O analyses of neutral sugars in soils using GC-Py-IRMS: problems, possible solutions and a first application. Rapid Communications in Mass Spectrometry 23, 3522–3532). In order to answer the question whether isotope fractionation and oxygen exchange reactions during litter decomposition affect the climatically controlled d18O values of plant derived sugars, such as for instance xylose and arabinose from hemicelluloses, we studied the compound specific d18O values of five different litter species having been decomposed in a field litterbag experiment for 27 months.