Trinickel boride is a compound of nickel and boron with chemical formula Ni3B.

[5] Trinickel boride can be obtained, as grains embedded in a nickel matrix, by heating Brown's P-1 and P-2 "nickel boride"catalyst to 250 °C.

This catalyst is produced by reduction of nickel salts with sodium borohydride.

[5] Trinickel boride can be obtained also by compressing nickel and boron powders with explosives.

[6] Recently it has been found that Ni3B can be formed (together with other nickel borides) by heating sodium borohydride with powdered nickel metal to 670 °C in a closed vessel, so that the released hydrogen creates a pressure of up to 3.4 MPa.