Practically, before being fed to the treatment plant, food waste (FW) is stored for up to a week in a storage tank under ambient temperature condition, which would have an impact on the bioenergy yield. In the present work, FW was stored at different temperatures (5 degrees C, 20 degrees C, and 35 degrees C) for 0 d, 1 d, and 2 d, and it was used as a feedstock for mesophilic H-2 fermentation. H-2 production curves were divided by three groups, finally attaining 1.7-1.8 mol H-2/mol hexoseaadea, 1.4-1.5 mol H-2/mol hexoseadded, and 1.2 mol H-2/mol hexoseadded, achieved from the (fresh, FW stored at 5 degrees C), (FW stored at 20 degrees C, and 35 degrees C for 1 d), and (FW stored at 35 degrees C for 2 d), respectively. The different performance was attributed to the growth of indigenous lactic acid bacteria such as Lactobacillus and Weissella during storage under high temperature condition. In addition, it was found that the activity of homoacetogenic reaction (R17, 4H(2) + CO2 -> Acetate) calculated by establishing metabolic flux balance was different depending on the H-2 production performance. The flux of R17 ranged 0.03-0.06 under low H-2 yield achieved conditions, while it increased to 0.10-0.17 those showing low H-2 yields. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.