Mechanical treatment by ball milling (BM) is an extremely versatile technique allowing for the synthesis of non-equilibrium structures and the production of nanostructured alloys for advanced materials science technology as well as the degradation of toxic compounds and the conventional mineral processing. In the present paper, we first review the recent developments in basic research on the kinetics of phase transformation under milling. Secondly, we propose a novel phenomenological macrokinetic approach and we test its capability of reproducing experimental data available in the literature. It was shown that the degree of conversion during BM can be correlated with the milling time and the ball to powder mass ratio. The proposed approach may provide a useful framework for the rationalisation of experimental results as well as the opportunity for further progress in the field of mechanochemical processing. (C) 2003 Elsevier Science Ltd. All rights reserved.