The well-aligned gadolinium silicide (GdSi1.7) nanowire arrays were prepared by reacting ultrahigh vacuum deposited Gd with silicon nanowire arrays. The diameter of nanowires is 100 nm in average and lengths, thereof, were about several micrometers. Field emission measurement showed that the turn-on field of gadolinium silicide nanowires is as low as 0.75 V/mu m at a current density of 10 mu A/cm(2). The current density of 1 mA/cm(2) can be reached at an applied field of 2.1 V/mu m. The field enhancement factor was determined to be 1222. Furthermore, the arrayed nanowires exhibit the ferromagnetic property at room temperature, which is attributed to magnetically uncompensated Gd atoms. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3529943] All rights reserved.