The effect of tetrabutylammonium (TBA) cations on phase transition within adsorbed adlayer and lifting of reconstruction at Au(111) electrode in sulfate solution and in presence of coumarin (CUM) has been studied by means of the cyclic voltammetry and differential capacity measurements. TBA cations retard the adsorption of sulfate anions which is responsible for the lifting of the reconstruction. Next, the presence of TBA cations in sulfate solution induces the appearance of phase transition in CUM adlayer for twice lower coumarin concentration and at much more negative potentials. Moreover, the protection against the sulfate anions adsorption which lifts the reconstruction is higher for CUM molecules than for TBA cations.