The low temperature conductivity σ (T) and the magnetoresistance (up to 8 T) of a phason disorder free pure Al65Cu20Ru15 quasicrystalline alloy, prepared by melt casting, has been investigated in the temperature range from 1.3 K to 200 K. In the temperature range 1.3 to 20 K the conductivity exhibits a $$\sqrt T $$ -variation, whereas for the range 20 to 200 K a linearT-dependence has been observed. The analysis of magnetoresistance data reveals the presence of weak localization and electron-electron interaction effects. The positive nature of the magnetoresistance indicates the presence of spin orbit scattering. The σ∞ $$\sqrt T $$ behaviour prevailing over such a wide temperature range has been observed for the first time for Al65Cu20Ru15. A quantitative analysis of the $$\sqrt T $$ -variation in terms of electron-electron interaction yields a very low density of states at the Fermi level.