A simplified method for the synthesis of thin film composite (TFC) membranes via interfacial polymerization was studied. Traditionally, the porous support layer is synthesized by phase inversion and subsequently impregnated with an aqueous amine solution before contacting it with an organic acyl chloride solution. In this simplified method, the phase inversion step and the impregnation with the amine monomer are carried out simultaneously by adding the amine to the coagulation bath before immersing the cast polymer film in it. This way, a two step process was successfully simplified into one step, combining both phase inversion and monomer impregnation of the support. Variation of synthesis parameters showed that a good membrane performance was achieved by adding 2 wt% m-phenylenediamine (as a monomer), triethylamine and sodium dodecyl sulfate (as a base/acylation catalyst and surfactant, respectively) to the coagulation bath. These synthesis conditions accord with the ones used in the traditional method. However, the polysulfone concentration, used for the synthesis of the support layer, could be lowered in the simplified method, without compromising in membrane performance. This method could lead to a more efficient, time and material saving synthesis of TFC membranes, which is of potential interest from a commercial and environmental point of view.