In the pursuit of sustainable energy, mature biomass gasification technology offers a combustion-free conversion of biomass into hydrogen and other products. This research introduces a novel integration of decomposition, pyrolysis, gasification, Pressure Swing Adsorption (PSA) and the Water–Gas Shift (WGS) reaction, providing a comprehensive analysis of hydrogen production from diverse biomass feedstocks—rice straw, bagasse and oil palm fronds—at varying temperatures (600, 700 and 800 °C). The results reveal that increasing the temperature enhances hydrogen yield, with rice straw yielding the highest hydrogen output at 282.35 kmol/h, followed by bagasse at 140.36 kmol/h and oil palm fronds at 125.29 kmol/h, attributed to rice straw's high lignin content. Innovative sub-zero temperature utilization emerges for efficient hydrogen separation, and the integration of appropriate heat exchangers is explored for economical gas purification. The captured CO2 holds promise for enhanced oil recovery or recycling into feed for improved conversion. Using Aspen Plus simulation, this study comprehensively analyses and models the process, highlighting a viable greener hydrogen production approach with significant implications for a sustainable energy future. Overall, this research presents a significant advancement in the efficient and sustainable production of hydrogen from biomass.