Bioaugmentation with an anaerobic fungus, Piromyces rhizinflata YM600, was evaluated in an anaerobic two-stage system digesting corn silage and cattail. Comparable methane yields of 328.8 +/- 16.8 mL g(-1) VS and 295.4 +/- 14.5 mL g(-1) VS and hydrogen yields of 59.4 +/- 4.1 mL g(-1) VS and 55.6 +/- 6.7 mL g(-1) VS were obtained for unaugmented and bioaugmented corn silage, respectively. Similar CH4 yields of 101.0 +/- 4.8 mL g(-1) VS and 104 +/- 19.1 mL g(-1) VS and a low H-2 yield (< 1 mL g(-1) VS) were obtained for unaugmented and bioaugmented cattail, respectively. However, bioaugmentation resulted in an initial increase in CH4 and H-2 production rates and also increased volatile fatty acid degradation rate for both substrates. Our study demonstrates the potential of bioaugmentation with anaerobic fungus for improving the digestibility of lignocellulose substrates for biogas and biohydrogen production. Crown Copyright (C) 2015 Published by Elsevier Ltd. All rights reserved.