The results of 4-aminopyrimidine (4-APM) impact studies on the double layer parameters at the R-AgLAFE/ chlorates(VII) interface in the solutions with different water activity as well as different properties of the mixed adsorption layer of 4-aminopirimidine – sodium 1-decanesulfonate (SDS) and 4- aminopyrimidine - hexadecyltrimethylammonium bromide (CTAB) at the electrode/solution interface are discussed.The differential capacity of the double layer (Cd) at the R-AgLAFE/ basic solution interface was measured using the electrochemical impedance spectroscopy. The zero charge potential (Ez) was determined using a streaming electrode, while the surface tension at the zero charge potential (Yz) was measured using the largest pressure method inside the mercury drop. It was proved that both the 4-aminopirymidine concentration and water activity have an essential effect on the doublelayer parameters on the R-AgLAFE/ chlorates(VII) interface. In the studied systems: 4-APM - SDS and 4-APM - CTAB, 4-aminopyrimidine dominance was observed.