Carbon supported alloy electrocatalysts based on Pt, Cu and Fe (atomic ratios Pt : Cu : Fe = 2 : 1 : 1 and 6 : 1 : 1) are prepared at various alloying temperatures and are characterized by XRD and TEM techniques. Powder XRD analyses show that Pt6CuFe clusters form a face-centered cubic structure (AuCu3 type), while Pt2CuFe clusters form an ordered alloy with a face-centered tetragonal structure (AuCu type) at higher temperature than 700 degrees C. Transmission electron micrographs reveal that the size of metal clusters increases gradually and size distribution becomes broader, as alloying temperature increases from 500 to 1100 degrees C.