The first hydrogenation of Ti_0.5Zr_0.5 (Mn_1-xFe_x) Cr1, x = 0, 0.2, 0.4 alloys in their as-cast and heat-treated states at room temperature are reported. For alloys with x = 0.2 and x = 0.4, heat treatment had for effect of changing the rate-limiting steps of the first hydrogenation in comparison with the as-cast alloys. Effect of air exposition was investigated. We found that, after a 10 days exposure to the air, the alloys could not absorb hydrogen. However, they quickly absorb hydrogen after mechanical deformation such as ball milling for a short time or one passes of cold rolling. Ball milling produced fast kinetics but with a loss of capacity while cold rolling gave faster kinetics than the as-cast state and with minimal loss of capacity. Therefore, cold rolling is considered to be the best way to regenerate the air exposed alloys.