Syngas fermentation processes with acetogens represent a promising process for the reduction of CO2emissions alongside bulk chemical production. However, to fully realize this potential the thermodynamic limits of acetogens need to be considered when designing a fermentation process. An adjustable supply of H2as electron donor plays a key role in autotrophic product formation. In this study an anaerobic laboratory scale continuously stirred tank reactor was equipped with an All-in-One electrode allowing forin-situH2generation via electrolysis. Furthermore, this system was coupled to online lactate measurements to control the co-culture of a recombinant lactate-producingAcetobacterium woodiistrain and a lactate-consumingClostridium drakeistrain to produce caproate. WhenC. drakeiwas grown in batch cultivations with lactate as substrate, 1.6 g·L−1caproate were produced. Furthermore, lactate production of theA. woodiimutant strain could manually be stopped and reinitiated by controlling the electrolysis. Applying this automated process control, lactate production of theA. woodiimutant strain could be halted to achieve a steady lactate concentration. In a co-culture experiment with theA. woodiimutant strain and theC. drakeistrain, the automated process control was able to dynamically react to changing lactate concentrations and adjust H2formation respectively. This study confirms the potential ofC. drakeias medium chain fatty acid producer in a lactate-mediated, autotrophic co-cultivation with an engineeredA. woodiistrain. Moreover, the monitoring and control strategy presented in this study reinforces the case for autotrophically produced lactate as a transfer metabolite in defined co-cultivations for value-added chemical production.