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Multiwalled BN nanotubes are grown from nickel boride catalyst particles by chemical vapor deposition at 1000−1100 °C using borazine, B₃N₃H₆, as the precursor. This precursor is generated in situ from molten salt that forms from mixtures of (NH₄)₂SO₄, NaBH₄, and Co₃O₄ at 300−400 °C. The BN nanotubes have concentric-tube structures, are free of internal closures, have crystalline walls, and exhibit lengths of up to ∼5 μm. The nanotubes often possess bulbous, flag-like, or club-like tip closures. A root-growth mechanism is proposed for the catalyzed process.