Kinetic data for the acid phase anaerobic digestion were presented in this study and the constants were determined with acid production rate and gas production rate. Process models based on continuous culture theory were used to describe the characteristics of the acid forming microorganisms and to enable further development toward utilization of the process in a more rational manner. Acid phase digestion can be separated with appropriate manipulation of hydraulic retention time in anaerobic digestion. Kinetic analysis of data from the various hydraulic retention times using a phase specific model obtained from the acid phase indicated maximum specific growth rate of 0.40/h, saturation constant of 2,000㎎COD/ℓ, yield coefficient of 0.35 ㎎VSS/㎎COD utilized and decay constant of 0.04/h for the acid production rate. Similar analysis of data for the gas production rate indicated maximum specific growth rate of 0.003/h, saturation constant of 2,200㎎COD/ℓ, yield coefficient of 0.0035 ㎎VSS/㎎COD utilized and decay constant of 0.06/h.