This paper reports the hydrogen generation potential of municipal solid waste incineration bottom ash from an incineration facility in Japan (N). Experiments were conducted by comparing the hydrogen generation potential among various particle fractions of bottom ash. Collected samples were dried and separated into four particle fractions (N1, N2, N3 and N4—from fine to coarse) and subjected to physical and chemical analyses prior to hydrogen generation. Hydrogen generation was conducted by mixing bottom ash samples with water at liquid to solid ratio (L/S) 5 and incubated at 40°C for 20 days. Gas pressure and concentration were measured at every 24 hours interval. The highest amount of hydrogen generation (cumulative) was observed in N2 particles at 20 days (41.5 l/kg dry ash). Finest particles (N1) and coarse particles (N4) showed the least hydrogen generation (cumulative) 22.5 l/kg dry ash and 25.2 l/kg dry ash respectively. The pH of liquid was observed to increase slightly after hydrogen production in each fraction.