We investigated a Cu-doped on a Mn-site at a compound of La 0.5Ca0.5MnO3 for an understanding of the influence on a structure and temperature transition of a magnetic. Characterization of the structure La0.5Ca0.5MnO 3 compound has been performed. The result of the X-ray diffraction XRD measurement shows that material at room temperature is a single phase with the orthorhombic structure and a space group Pnma with lattice parameters a=5.41792Å, b=7.63906Å, c=5.42265Å and α=β=γ= 90°. From the energy dispersive X-ray spectroscopy EDAX, we get the composition is La0.493Ca0.528Mn02.57. The compound of a La0.5Ca0.5MnO3 with a Cu-doped (La0.5Ca0.5Mn1-xCuxO3, with 0≤x≤0.2) is in characterization process. From the previous experiment, a Cu was doped on a Mn-site at the La0.1Ca 0.9MnO3 compound (La0.1Ca0.9Mn 0.9Cu0.1O3), we obtained that it also crystalilizes in the orthorhombic Pnma, but the lattice parameters is decreasing if it is compared without a Cu doping. This might be due to a Jahn-Teller distortion, which change the average of an (Mn,Cu) - O bond length and an (Mn,Cu) - O - (Mn,Cu) bond angle.