Multi-walled boron nitride (BN) nanotubes having cylindrical structure were synthesized employing the mechanothermal process. In this process hexagonal boron nitride powder (hBN) was first ball milled for 50-100 h using a high-energy ball mill and the ball-milled samples were annealed in N-2 atmosphere for about 10 h in the temperature range of 950-1300 degrees C. The BN nanotubes exhibited a well-crystallized hexagonal structure with about 25-40 nm in diameter and up to 1 mu m length. These BN nanotubes were well characterized using various techniques, such as, XRD, SEM, TEM and Raman Spectroscopy.