The interaction of nitrogen with liquid and solid silicon at high temperature is investigated in an electromagnetic levitation set-up. It is shown that the nucleation undercooling of Si decreases monotonically from 300 to 1 K when the concentration of nitrogen in the solidified droplet increases from 0 to 600 ppmw. Several alpha- and beta-Si3N4 morphologies are observed and their growth conditions are linked to the various stages of the Si droplet cooling down. It follows that electromagnetic levitation is a valuable tool for investigation of the chemical behavior of highly reactive liquids at high temperature. (C) 2011 Elsevier B.V. All rights reserved.