Fe-P ultrafine amorphous alloy particles have been synthesized by chemical reduction of various iron precursors such as FeCl2·4H2O, FeCl3·6H2O, and Fe(OAc)2 under different preparation mediums, viz., H2O, ethanol/H2O, and isopropyl alcohol/H2O. The synthesized materials were characterized by X-ray diffraction, inductively coupled plasma-atomic emission spectroscopy, N2 sorption, transmission electron microscopy, X-ray photoelectron spectroscopy, and electron diffraction. The results indicated the existence of amorphous nature of Fe-P materials even when the treatment temperature was up to 400 °C. The structure, morphology, and composition of Fe-P nanoalloys have been significantly influenced by the iron precursor and the type of solvent. Dehydrogenation of ethanol has been carried out in order to evaluate the catalytic properties of the Fe-P nanoalloys and related to the surface properties of Fe-P nanoalloys. Sample Fe89.1P10.9 prepared with FeCl3·6H2O in isopropyl alcohol/H2O solvent showed the highest activity owing to its high surface area and high turnover frequency.