The kinetics of interstitial iron precipitation inp‐type silicon are investigated. During annealing, the iron charge state is controlled by the applied reverse voltage and its effect on the precipitation is studied. We observe that iron in the neutral charge state (Fe0i) precipitates preferentially in three‐dimensional nucleation centers while Fe+ivanishes in the dislocation lines (rod‐like nucleation centers). These centers are created during the fast cooling procedure necessary to dissolve iron in the silicon matrix.