Formation of multi-twin Au particles on the electrode in electrolyte solution is strictly controlled by electrode potential, which is almost equal to the potential induced reconstruction of Au single crystal surfaces. Lattice shortening caused by negative electrode potential (SCE) is responsible for these two phenomena, which is essentially different from the crystal habit depending on the growth rate of crystal surfaces. Most fcc metals form multi-twin particles when the electrode potential keeps at negative potential (SCE), but the stability of the multi-twin particles formed on the electrode highly depends on the metals. Unstable multi-twin particles react with H₂O to form single crystal oxide particles. Cu₂O and NiO can not be thermodynamically formed at the potential for the formation multi-twin particle, but single crystals of Cu₂O and of NiO are practically formed. When the electrode is kept at the OPD (over potential deposition) for Au ions and UPD (under potential deposition) for Cu ions on Au surface, CuAu alloy particles are grown by layer-by-layer deposition mechanism of Au and Cu ions. Although the electrode potential for the layer-by-layer deposition of Au and Cu is higher than the critical potential for the formation of multi-twin particles of Au and Cu, we can recognize the formation of multi-twin CuAu alloy particles. It is speculated that the adsorption of Cu⁺ ion on Au layer may induce the lattice contraction so that the multi-twin alloy particles are formed.