We have studied the effects of an organic additive, saccharine N-propane sulfonate, on the microstructures, magnetic properties, and magnetoimpedance of electroplated Ni - Fe Permalloy thin films. Compared to thin films prepared with a pure inorganic electrolyte, the Ni - Fe Permalloy thin films electroplated with electrolytes containing the additive have different crystalline orientation, grain size, surface roughness, coercivity, permeability, and magnetoimpedance. There is a strong correlation between the observed structural changes and the changes in the magnetic properties, such as in the coercivity and permeability. The changes are also dependent on the structure of the electroplating cells. By using an appropriate plating cell, the coercivity can be reduced from 0.36 to 0.08 Oe. These changes in the magnetic properties result in an increase in the magnetoimpedance by 31%. (c) 2008 The Electrochemical Society.