Presented work investigates conditions at the electrode/solution interface leading to incorporation of Fe(OH)(3) into CoFe thin films. The oxygen content and coercivity of CoFe films is studied as a function of Fe3+ ion concentration in the solution. These results are analyzed through the scope of analytical model describing the oxygen presence in CoFe films as a consequence of Fe(OH)(3) incorporation phenomenon. The scanning transmission electron microscopy study with nanometer scale resolution for composition analysis has elucidated the alteration in grain structure of CoFe films due to Fe(OH)(3) incorporation. These findings directly implicate Fe(OH)(3) incorporation as a reason for the increase in coercivity of CoFe films. (C) 2013 Elsevier Ltd. All rights reserved.