Consolidated bioprocessing (CBP) of wheat straw (WS) pretreated via ammonia fiber expansion (APEX) for hydrogen production was discussed in this study. Results indicate that rotted wood crumb is a good mixed natural-microflora seed source for biohydrogen production from WS. The hydrogen-producing capability of the inoculum could be improved by an enrichment treatment. In order to enhance the digestibility of WS, APEX pretreatment conditions were investigated. The optimal conditions were determined to be 100 degrees C, 1:1 (w/w) ammonia to biomass loading, and 30min residence time. The yield of H-2 was 67.8% higher using AFEX-pretreated WS than using untreated material. Moreover, degradation products derived from APEX pretreatment exerted no impact on hydrogen fermentation if controlled below 1.5% substrate-loading-equivalent. In addition, the maximum AFEX-WS conversion and H-2 production were achieved at substrate loading of 0.8%. This work indicates that CBP offers a promising platform for direct and cost-effective cellulosic hydrogen production compared to separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF). Crown Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.