Biomass steam gasification is the most effective thermochemical conversion route for producing enriched biohydrogen from various biowaste feedstocks. Such processes are designed by solving constrained model equations and applying these to estimate the product composition against various feedstocks. In this paper, robust methods for optimizing the biomass steam gasification process to produce H₂ are presented. Thermodynamic models were developed and optimized to determine new competitive correction factors based on experimental data obtained from previous studies to correct the errors associated with these models. The newly introduced correction factors were applied to the equilibrium constants and Gibbs free energy equations of the thermodynamic models. The proposed corrected models were validated and compared with existing modeling and experimental studies. The H₂ production from rice husks was in good agreement with the experimental composition. The overall root-mean-square errors of the stoichiometric and non-stoichiometric thermodynamic models decreased from 2.89 to 2.36 and from 4.53 to 2.46, respectively. Finally, the proposed models were applied to wood biomass and subjected to parametric analysis by varying the operating parameters, including temperature, moisture content, and steam to biomass ratio. This study will help to address the issues related to biohydrogen production from thermochemical conversion processes using different biomass feedstocks.