Hydrogen absorption-desorption properties of Ti-M-V-B (M=Cr, Mn) metastable BCC alloys have been examined at hydrogen pressures of 0.01-7MPa and a temperature of 303K using an automatic Sieverts apparatus. Ti 3 7 Mn 2 5 V 3 8 B x alloys were prepared by arc melting and Ti 3 1 Cr 3 0 V 3 9 B x (x=0, 6) alloys were prepared by a suction casting method. The crystal structure and lattice parameters of the alloys were examined by an X-ray diffraction analysis (XRD) in addition to pressure-composition isotherms. The Ti 3 7 Mn 2 5 V 3 8 alloy and the Ti 3 1 Cr 3 0 V 3 9 B x (x=0, 6) alloys were BCC single phase and had large hydrogen storage capacities.