This study reports the effect of inoculum addition on bio-hydrogen production from waste peach pulp by dark fermentation. Batch mode experiments were done at constant 200 g/L waste peach pulp concentration by varying the inoculum addition between 0 and 10% (v/v). The highest hydrogen yield (123.27 mLH(2)/gTOC) was obtained at 5% inoculum addition with 46% hydrogen content in the gas phase. On the other hand highest hydrogen formation rate (35.6 mLH(2)/h) and TOC removal (25.17%) were obtained with 10% sludge addition. Hydrogen production yield increased by increasing the sludge addition from 0 to 5% and then decreased at higher values. The control bottle showed a significant performance in terms of hydrogen production indicating the contribution of natural microflora for hydrogen gas formation. However, hydrogen formation rate and yield increased significantly with inoculation. The addition of 5% (v/v) inoculum resulted most convenient hydrogen formation compared with other ratios. The minimum amount of inoculum per substrate at 5% (v/v) was 0:009 g biomass/g TS. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.