The existence of a new metallic carbide of composition Th 3Ni5C5 was reported in the literature in 1991. This compound is a new orthorhombic prototype structure. In this work we report a reinvestigation of the synthesis of this material and we find that the Th 3Ni5C5 compound is a new bulk superconducting material. Despite the high concentration of Ni in this compound, we find bulk superconductivity with superconducting critical temperature of Tc = 5.0K and an upper critical field of μoHc2 = 5.8T. Details of the superconducting state with specific heat, magnetization, and resistivity measurements are discussed. © 2011 IOP Publishing Ltd.