The technique of the supported‐liquid membrane (SLM) has been employed to remove phenol from aqueous streams. The sulfuric acid salts of trioctylamine (TOA salts), which have been produced from the reaction of trioctylamine (TOA) and sulfuric acid, dissolved in TOA, have been used as the carrier material which filled in the pore of the membrane. 1‐octanol has been added to the organic solution to make it a homogeneous organic solution. The transport of phenol is expressed by the permeability of the phenol which is an index to indicate the extraction capability of phenol through the supported‐liquid membrane. VVLP, GVHP and PP membranes have been employed to examine the characteristics of extraction. Effects of the operating conditions and parameters, such as the initial concentration of phenol in the aqueous phase, the initial concentration of sulfuric acid in the feed solution, the initial concentration of sodium hydroxide in the stripping solution and the initial concentration of TOA salts in the VVLP membrane on the permeability were investigated in detail.