Abstract: Abstract: During anaerobic fermentation is strongly influenced by temperature and volatile fatty acids (VFAs). When the temperature in anaerobic reactors is too high, the VFAs are easy to accumulate, especially acetate and propionate. High VFAs will inhibit the activity of methanogens, the fermentation process as well as the methane yield will become unstable even make the anaerobic system failed. In order to investigate the ability of adapting different concentration of acids and temperature, batch experiments with different concentrations of acetate and propionate were carried out at both mesophilic and thermophilic conditions. Modified Gompertz model and first order model were used to analyze the methane production kinetics. The inoculum was got from coffee mate anaerobic digestion, because coffee mate contains 2% protein, 34% fat and 56% carbohydrates, which can simulate the real ingredients in anaerobic fermentation. The concentrations of acetate acid were set for 0, 2 000, 5 000, 10 000 and 20 000 mg/L; and the concentrations of propionate were set for 0, 500, 1 000, 2 000, 4 000 and 8 000 mg/L. In addition, sodium hydroxide was used to adjust the pH value in a range of 7.2-7.6 in every batch bottle, and every concentration had 3 parallels to ensure the veracity of this experiment. The result showed that both of acetate and propionate degradation faster at the lower concentration. Acetate was easily degraded at mesophilic condition, when the concentration of acetate was 5 000 mg/L; mesophilic reactors had the maximum methane production rate which was 101 mL/d, while the thermophilic reactor had the maximum methane production rate which was 77 mL/d when the acetate concentration was 10 000 mg/L. With the acid concentration increasing, methane production rate decreased and the thermophilic reactor had a higher tolerance for the acetate concentration. In contrast, propionate was easily decomposed under the thermophilic condition and the lag phase under mesophilic was greatly affected by the acid concentration; when the propionate concentration increased from 500 to 4 000 mg/L, the lag phase doubled under the mesophilic condition while a half fold increase under the thermophilic condition. The maximum methane production rate was 96 mL/d when the concentration of propionate was 4 000 mg/L, while the maximum methane production rate under mesophilic condition was 75 mL/d when the concentration of propionate was 4 000 mg/L as well. The lag phase of gas production was longer at higher acid concentration, while the first-order kinetic constants reduced. In addition, the degradation rate constant of both mesophilic and thermophilic under same acid condition showed that the effect of temperature on anaerobic degradation is greater than that of acid concentration to some extent.