Both perennial grasses and corn biomass residues are non-edible for humans and have high carbohydrate contents that make them promising raw materials for biofuel production. This study evaluated perennial grasses (miscanthus and switchgrass) and corn-based biomass materials (corn stover, stalk, cob, husk, and bran) for high-yielding hydrogen gas production by aqueous-phase reforming (APR). The biomass materials were dissolved in subcritical water to obtain hydrolysates for use as feed solutions in APR. The dissolution experiments showed that hydrolysis percentages and total organic carbon releases were considerably higher in corn biomass fractions as compared to perennial grasses. The highest (66.7 mL H-2) and lowest (27.0 mL H-2) hydrogen yields were observed when miscanthus and corn bran biomass hydrolysates, respectively, were used as the feed solution. Hydrogen production yields were found to be in the following descending order: miscanthus > corn cob > corn stover > switchgrass > corn husk >= corn stalk >> corn bran. In general, the biomass hydrolysates that had less organic carbon resulted in higher hydrogen production. Hydrolysis and gasification results for corn husks from various types of corn (field corn, sweet corn, seed corn, and popcorn) were different. The findings of this study will be beneficial for selection of the right biomass material for production of a specific value-added product from biomass. This study focused on biofuel hydrogen gas, which has the highest specific energy content of all conventional fuels.