The structure and electrochemical properties of quasicrystalline cast Al$_{65}$Co$_{20}$Cu$_{15}$ and Al$_{72}$Co$_{18}$Ni$_{10}$ alloys cooled at 50 K/s are studied in this work. The methods of quantitative metallography, scanning electron microscopy, X-ray analysis and energy dispersive X-ray spectrometry are applied. Corrosion behaviour in 5% aqueous NaCl solution (pH = 6.9–7.1) is investigated by gravimetric and potentiodynamic methods. Not less than 60–65% vol. of quasicrystalline decagonal phase is observed in the structure of the alloys. The corrosion of the alloys in the aqueous solution of sodium chloride proceeds under electrochemical mechanism. Both alloys have close values of stationary potentials (-0.43 V for the Al$_{65}$Co$_{20}$Cu$_{15}$ alloy and -0.40 V for the Al$_{72}$Co$_{18}$Ni$_{10}$ alloy). Current density for the Al$_{63}$Co$_{24}$Cu$_{13}$ alloy equals to 0.18 mA/cm$^2$, and that for the Al$_{69}$Co$_{21}$Ni$_{10}$ alloy—0.12 mA/cm$^2$. Gravimetric measurements show that the mass of the samples is grown during first 4 days of model corrosion tests, but during the following 4 days of experiments the mass remains almost unchanged. The result obtained is explained by the formation of a protective oxide film on the surface of the samples. The corrosion resistance of Al$_{69}$Co$_{21}$Ni$_{10}$ alloy in the saline solution of sodium chloride slightly exceeds the one of Al$_{63}$Co$_{24}$Cu$_{13}$ alloy. Scanning electron microscopy shows the marks of pitting corrosion on the surface of the investigated alloys. The pits with size $\sim$10 $\mu$m appear mostly in the defected areas. The corrosion mainly occurs at the boundaries of the primary and the peritectic phases. Both the quasicrystalline cast Al$_{65}$Co$_{20}$Cu$_{15}$ and Al$_{72}$Co$_{18}$Ni$_{10}$ alloys may be recommended for the application as the fillers of macroheterogeneous composite coatings designated for the performance in the conditions of sea climate.