To evaluate the kinetic feasibility of the uncatalyzed rTCA cycle under prebiotic conditions, we performed microkinetic modeling simulations of the discovered network (Fig. ). Microkinetic modeling simulations were performed at 348.15K and 1 atm pressure with excess H2 and CO2, which reflect favorable conditions for promoting carbon fixation (i.e., hot and with ample H2 as fuel). The system was initialized uniformly with a mole fraction of 0.0004 for all main rTCA cycle species, while maintaining excess CO2 and H2 with mole fractions of 0.82 and 0.16 respectively. Although CO2 and H2 have different aqueous solubilities (CO2 being orders of magnitude greater than H2), the simulations assume their sustained availability to probe the intrinsic reaction kinetics. Under these idealized conditions, a kinetically viable cycle would show significant fluxes through all participating species with monotonic accumulation of acetic acid. In contrast, the microkinetic simulations show an accumulation of the main cycle species 2-oxoglutarate (S7) and oxaloacetate (S1), which is consistent with their thermodynamic minima along the main cycle (Fig ). Main cycle flux is also lost to the low barrier off-target reaction, R4, of 0.54 mol⸱m -2 ⸱s -1 (Fig. ). Despite 2-oxoglutarate (S7) being a local energetic sink, completion of the cycle is energetically favorable as the free energy gain is directly proportional to the number of cycles completed. If the cycle terminates at 2-oxogutarate (S7) there will be a one-time free energy gain of -18 kcal⸱mol -1 ; however, completion of the cycle provides -12.1 kcal⸱mol -1 free energy gain per cycle which will grow linearly with the number of cycles. The microkinetic simulations indeed recapitulate the monotonic increase in acetic acid (Fig ), but it is extremely small (5 x 10 -13 ) despite the long timescales that were simulated due to the presence of kinetic sink in 2-oxoglutarate and high barriers throughout the cycle. This pronounced flux localization demonstrates that even under favorable conditions with excess reactants, the uncatalyzed cycle cannot sustain the distributed reaction flux necessary for effective carbon fixation.