Two Al alloys with 1 and 3 at% Co were prepared by arc-melting of Al and Co in argon. The corrosion behavior of the as-cast alloys was studied in a NaOH aqueous solution (0.01 M). Furthermore, a hydrogen evolution was investigated by volumetric measurements. The results were compared with pure Al. The alloy with 1% Co was the least corrosion resistant and evolved most hydrogen. The presence of Al9Co2 in the eutectic facilitated hydrogen evolution and contributed to corrosion activation. The results can be used for the design of Al-Co alloys for hydrogen generation.