Nb75M25 (M = Al, Si, Ga, Ge, and Sn) alloy ingots were prepared by the conventional arc-melting method and then were directly reacted with high purity hydrogen of 0.1 MPa in an arc-melting chamber without exposing the ingots to air. As the clean surface of the arc-melted ingots is preserved, the ingots rapidly absorb a large amount of hydrogen without any activation treatments and disintegrate violently into fine particles. The disintegration of ingots depends on the M element. The collected particles are investigated by x-ray diffraction, electron microscopy, chemical analysis, and thermal analysis. The particles are hydrides of Nb75M25 after hydrogenation and have a sharp-edged polygonal appearance. After dehydriding, fine Nb3M powders with A15 crystalline structure are obtained except for Nb75Si25. In comparison with the atomized Nb3M powders, the Nb3M powders prepared by the present study have a smaller average particle size and lower impurity contents.