<p>Tequila vinasses, an acidic and highly loaded wastewater, pose severe environmental challenges but also represent a promising substrate for sustainable bioenergy recovery. Anaerobic digestion of tequila vinasses has been widely employed for methane-rich biogas production; however, its application for biohythane generation—a mixture of H₂ and CH₄ with enhanced combustion properties and potential as a renewable natural gas substitute—remains largely unexplored. In this study, a two-stage anaerobic digestion system was operated under an alkalinity-based control (ABC) scheme that directly integrates the alkalinity index (α) as a control variable in a cascade structure to mitigate volatile fatty acid (VFAs) fluctuations. By maintaining α below a defined safety threshold, the methanogenic reactor achieved robust and stable performance (0.28&#xa0;L-CH₄ g-COD_removed⁻¹), even under increasing organic loading conditions. Although moderate hydrogen yields were obtained (0.10 ± 0.03&#xa0;L-H₂ g-COD_removed⁻¹), CH₄ production governed total energy recovery, highlighting the central role of methanogenic stability in biohythane-oriented systems. The two-stage process reached an overall productivity of 1.90&#xa0;L-biogas L^− 1 d^− 1, containing 17% H₂ and 49% CH₄ (25.5% and 74.5%, respectively, after CO₂ removal). These findings demonstrate that a simple-to-implement alkalinity-based control strategy can enhance methanogenic robustness, support downstream upgrading feasibility, and provide a scalable pathway toward circular and low-cost bioenergy integration within tequila distilleries.</p>