A kinetic model was applied to improve determination of the sugar recovery standard (SRS) for biomass analysis. Three sets of xylose (0.10–1.00 g/L and 0.999–19.995 g/L) and glucose (0.206–1.602 g/L) concentrations were measured by HPLC following reaction of each for 1 h. Then, parameters in a kinetic model were fit to the resulting sugar concentration data, and the model was applied to predict the initial sugar concentrations and the best SRS value (SRSp). The initial sugar concentrations predicted by the model agreed with the actual initial sugar concentrations. Although the SRSe calculated directly from experimental data oscillated considerably with sugar concentration, the SRSp trend was smooth. Statistical analysis of errors and application of the F-test confirmed that application of the model reduced experimental errors in SRSe. Reference SRSe values are reported for the three series of concentrations. Biotechnol. Bioeng. 2012;109: 300–305. © 2011 Wiley Periodicals, Inc.