YBa 2 Cu 3 O 7 (Y123) is a superconductor material discovered in 1987 and its transition temperature is above the liquid nitrogen temperature. It is known that superconductor samples produced by the solid-state reaction route are very often sintered in air atmosphere. However, in the presented work, Y123 was prepared by the same technique using a sintering ambient composed of a mixture of oxygen and argon gases for the rst time. Critical current densities of the samples were calculated using results of magnetization measurements. It was obtained from magnetization analysis that all the samples exhibited superconductor character. It was also observed that the sample sintered in the 50% oxygen and 50% argon atmosphere showed the highest critical current density