Bio-pretreatment using a fungal consortium to enhance the efficiency of lignocellulosic biohydrogen production was explored. A fungal consortium comprised of T. viride and P. chrysosporium as microbial inoculum was compared with untreated and single-species-inoculated samples. Fungal bio-pretreatment was carried out at atmospheric conditions with limited external energy input. The effectiveness of the pretreatment is evaluated according to its lignin removal and digestibility. Enhancement of biohydrogen production is observed through scanning electron microscopy (SEM) analysis. Fungal consortium pretreatment effectively degraded oat straw lignin (by >47% in 7 days) leading to decomposition of cell-wall structure as revealed in SEM images, increasing biohydrogen yield. The hydrogen produced from the fungal consortium pretreated straw increased by 165% 6 days later, and was more than produced from either a single fungi species of T. viride or P. chrysosponium pretreated straw (94% and 106%, respectively). No inhibitory effect on hydrogen production was observed.