Novel soft magnetic materials can be obtained by altering the material properties of soft magnetic alloys, including the morphology, composition, crystallinity, and grain size. The magnetic properties (such as saturation magnetization and coercivity) of soft magnets are significantly dependent on the grain boundaries, which control the magnetic domain wall movement. Herein, we develop a two-step electroless plating method to control the morphology and grain size of FeCo films, to obtain excellent magnetic properties. To control the degree of polarization, the chemical composition was altered by varying the electroless plating conditions, such as electrolyte concentration and reaction temperature. The grain size and crystallinity of the FeCo alloys were dramatically affected by the reaction temperature, because grain growth occurs dominantly at 90 degrees C, whereas nucleation only occurs at 50 degrees C. By simply controlling the electrolyte temperature, an FeCo film embedded with micron-sized FeCo grains was synthesized. The high crystallinity and large grains allowed high magnetization, and the high magnetic exchange between FeCo grains of different sizes gave low coercivity. (C) 2019 The Electrochemical Society.