This fundamental work investigated the removal of sodium dodecyl sulfate (SDS) from highly concentrated samples by electromembrane extraction (EME). SDS concentrations were in the range of 0.1-1.0% w/v, covering both sub- and super-critical micellar concentrations (CMC). Under optimal conditions, we extracted SDS from 100 mu L aqueous sample, through 3 mu L supported liquid membrane (SLM) and into 200 mu L 10 mM NaOH in water as waste solution. The SLM comprised 1.0% w/w Aliquat 336 in 1-nonanol, and extraction voltage was 5 V. From 0.1% SDS samples, EME removed 100% during 30 minutes operation (100% clearance). SDS concentration above the critical micellar concentration (CMC) challenged the capacity of the system. Thus, to reach 100% clearance from 0.5% samples, we extracted for 120 minutes and replenished the SLM after 60 minutes. Increasing the membrane area of the SLM from 28 mm(2)to 43 mm(2)provided 100% clearance from 0.5% samples after 30 min EME. Complete clearance of 1.0% SDS samples was not achieved under the tested conditions, and maximal clearance was 60%. Mass balance experiments demonstrated that most of the removed SDS is trapped in the SLM, rather than transferring to the waste solution. For super-CMC samples, aggregation of SDS in the SLM exceeded the SLM capacity and impeded further mass transfer.