Alloying reactions of metal films deposited on chemically etched GaAs and InP surfaces, (Ni/Au-Ge and Ni films for GaAs, Au and Au-Zn films for InP), were studied using micro-probe Auger electron spectroscopy, X-ray photoelectron spectroscopy, reflection and transmission electron diffraction, and X-ray diffraction. The chemically etched surfaces are covered with thin native oxide layers (5-10 Å thick). Metallization without interfacial native oxide layers is realized by depositing metals, (Ni for GaAs and Au for InP), which have a capability to produce compounds with both III and V group elements.