The magnetization reversal of thin iron films at 300°and 80°K was observed by means of the Kerr magneto-optical effect. It was found that the coercive force of a wall increases during the time the wall is fixed in one place of the film. This leads to the conclusion that the dynamics of magnetization reversal is influenced by a Richter-type aftereffect. A new model of wall motion is proposed. © 1968 The American Institute of Physics.