Six triethylammonium-based protic ionic liquids (PILs) and two molten salts were synthesized via a proton transfer reaction from sulfonic acid to triethylamine (TEA). The PILs were characterized by 1H NMR, 13C NMR, 1H/15N NMR and FT-IR spectroscopic methods. The phase behavior of the PILs was studied using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The temperature dependences of the PILs electrical conductivity, viscosity, and electrochemical stability window (ECW) were studied. The highest electrical conductivity and ECW values are registered in triethylammonium triflate. The thermal and electrochemical characteristics of the salts obtained in this work have been analyzed in comparison with the literature data by the properties of triethylammonium-based salts with sulfonic acids.