We have studied the influence of the substitution of Al for Ni in the ternary systems RENi_5-xB_x (RE=Gd, Y). The compounds synthesized in the pseudo-ternary systems RENi_4-xAlB_x (RE=Gd, Y) were studied in terms of their crystal structure, chemical composition and hydrogen sorption properties. Most of the compounds obtained in these systems crystallize with the CeCo₄B-type structure RENi₃AlB, with Al atoms replacing Ni. The partial replacement of Ni by Al observed leads to a decrease of lattice parameters compared to ternary RENi₄B compounds. The new pseudo-binary phase GdB₃ was also observed in this study for the first time.  Finally, it is reported that the compounds do not show any affinity towards hydrogen, with no absorption observed.