Low-input high-diversity (LIHD) mixtures of native grassland perennials were subjected to a supercritical treatment process with the aim of obtaining hydrogen-rich gases. The process was studied based on the following treatment variables: reaction temperature (374 degrees C to 575 degrees C, corresponding to a pressure range of 22.1 to 40 MPa), residence time (10 to 30 min), biomass content in the feed, and catalysts (0% to 4% NaOH and solid alkali CaO-ZrO2). The gaseous phase produced from gasification of LIHD primarily consisted of hydrogen (H-2), with a mixture of carbon monoxide (CO), methane (CH4), and carbon dioxide (CO2). The statistical significance of treatment variables was evaluated using analysis of variance (ANOVA). It showed that at the level of P<0.05, temperature, catalysts, and biomass content in the feed significantly affected gas yields, while residence time was not significant.