A systematic study of the effect of magnetic field (h) on the Hubbard model has been carried out at half-filling within dynamical mean fieldtheory. In agreement with previous studies, we find a zero temperature itinerantmetamagnetic transition, reflected in the discontinuous changes in magnetization aswell as in the hysteresis, from a paramagnetic (PM) metallic state to a polarizedquasi-ferromagnetic (QFM) state, at intermediate and large interaction strengths (U).The jump in magnetization vanishes smoothly with decreasing interaction strength, and at a criticalU, thetransition becomes continuous. The region of ‘coexistence’ of the PM and QFM solutions in the field–U plane obtained in this study agrees quantitatively with recent numerical renormalizationgroup calculations, thus providing an important benchmark. We highlight thechanges in dynamics and quasiparticle weight across this transition. The effectivemass increases sharply as the transition is approached, exhibiting a cusp-likesingularity at the critical field, and decreases with field monotonically beyondthe transition. We conjecture that the first order metamagnetic transition is aresult of the competition between Kondo screening, that tries to quench the localmoments, and Zeeman coupling, which induces polarization and hence promotes localmoment formation. A comparison of our theoretical results with experiments on 3He indicate thata theory of 3He based on the half-filled Hubbard model places it in a regime of intermediate interactionstrength.