Ultrathin films of Fe and Ni on a Cu(100) surface exhibit a reorientation of the magnetization. For Ni films the magnetization is first in-plane and rotates out-of-plane upon increasing the thickness. This is in contrast to the situation for Fe films. We investigated how the transition evolves between the two endpoints by using FexNi1-x/Cu(100) alloy films. By means of MOKE we have determined the easy axis for different concentrations. ©2002 IEEE.