Upper mesophilic temperature acclimation of halophilic, hydrogen-producing bacteria from salt fields was investigated in this study, along with the changes in microbial abundance during an-aerobic digestion (AD) process. Genomic approaches such as PCR-denaturing gradient gel elec-trophoresis (DGGE) and next-generation sequencing (NGS) were performed to profile the mi-crobial communities. During AD, there was a significant abundance of Halanaerobacter lacunarum at 48°C followed by the increase in hydrogen yield, signifying potential contribution from the halophile in the hydrogen production. A decrease in the dominance of H. lacunarum and Halan-aerobium fermentans at 42°C, likely due to an increase in other bacterial species, was noted but their dominance significantly increased at temperatures of 45°C and 48°C. This investigation provides valuable insights in highlighting the potential of Halanaerobium sp. and the other halo-philic bacteria to adapt under upper mesophilic temperature conditions and synthesizing hy-drogen. The findings in the present study also underscore the importance of optimizing temper-ature and pH conditions to maximize hydrogen yield during high-salt anaerobic digestion.