We have developed a procedure for the fabrication of Er-Ni liquid alloy ion sources. The source is tested and analyzed in a MicroBeam 150 focused ion beam system. Our experimental results show that an Er2+ target current of 95-100 pA was produced, representing 50% of the total target current. The ion emission current-voltage slope is similar to 36 mu A/kV. Source lifetimes are generally larger than 20 h. The alloy oxidizes quickly once it is exposed to air. This must be minimized to ensure proper source performance.