The present work was aimed at determining the efficacy of the extant respirometric technique to measure the biodegradation kinetic parameters of surfactant linear alkylbenzene sulfonate (LAS) and alkyl sulfate (AS) in laboratory and field activated sludge systems. LAS and AS are most common used in the commercial and personal usage and present in the influent of the wastewater treatment plant. To simulate the activated sludge system, two 1-L porous pot (65 [Mu] stainless steel mesh) reactors were fed synthetic wastewater with a COD of 200 mg/L including 2 mg/L LAS and 1 mg/L AS to cultivate the activated sludge for respirometer tests. To evaluate the influence of the operating conditions, the reactors were operated in parallel at a range of HRT and SRT conditions. The biodegradation responses of LAS were measured using a respirometric method, and the extant kinetic parameters were evaluated using the Monod model. The ranges of the measured extant kinetics of LAS were,[Mu] of 0.02 - 0.20 h−1, q of 0.05 - 0.33 h−1, K[Subsript s] of 0.06 - 0.78 mg COD/L, and Y of 0.44 - 0.70 mg biomass COD formed / mg LAS COD utilized. The ranges of the measured extant kinetics of AS were [Mu] of 0.18 - 0.29 h−1, q of 0.32 - 0.56 h−1, K[Subscript s] of 0.19 - 1.27 mg COD/L, and Y of 0.43 - 0.70 mg biomass COD formed/mg LAS COD utilized. To evaluate the efficacy of the respirometer technique, field tests of extant kinetic parameters for LAS and AS biodegradation were conducted at three municipal wastewater treatment plants operated at different conditions. The field results were found to be similar to the results from laboratory systems operated to simulate the field conditions, but with larger variability. The predicted effluent concentrations using the extant kinetics from the experiments were compared with the field-measured results, and the results showed accurate predictions, especially for LAS. These results confirm the applicability of the extant respirometric technique to obtain the accurate biodegradation rates of surfactants in laboratory and field systems.