The effect of manganese addition on hydrogen storage performance of vanadium-based BCC alloys was investigated by measuring mainly pressure-composition (P-C) isotherms at 303K. Annealing heat-treatment was also considered in selected cases. The XRD patterns showed BCC single phase in all the alloys. With increasing Mn content, the lattice parameters decreased linearly, thus resulting in an increase in plateau pressure and a reverse effect on maximum hydrogen storage capacity. However, an effective hydrogen storage capacity as high as 1.92 wt.% was achieved at x = 0.075. V-Ti-Mn alloys showed a surprisingly flat desorption plateau, but lots of absorbed hydrogen cannot desorb at ambient temperature. Although V0.44Ti0.20Cr0.12Mn0.12Fe0.12 alloy did not show the first plateau, both the maximum and effective hydrogen storage capacities were very low.