Synthesis gas (syngas) composed of carbon monoxide (CO), carbon dioxide (CO₂), and hydrogen (H₂) is one of the promising candidates for renewable energy and can be converted into biofuels by syngas fermentation. However, the scaling up this systems is limited by poor gasliquid mass transfer. In this study, the typical electrolytes for microorganism cultivation were applied for CO-water mass transfer improvement. As a result, smaller gas bubbles were generated in inverse proportion to electrolyte concentration, hence providing increased mass transfe. The highest volumetric mass transfer coefficient (k_La) of 568.8 /hr was achieved using 5 % NH₄Cl.