Abstract: A process of producing a ceramic arc tube for a high-pressure metal-vapor discharge lamp, including a translucent ceramic tube, and at least one end cap which closes corresponding at least one end of the ceramic tube and which supports a discharge electrode. A green ceramic tubular body which gives the ceramic tube is formed of a first ceramic material, whereas at least one green end cap which gives the at least one end cap is formed of a second ceramic material of a same kind as the first ceramic material. Each green end cap has a cylindrical portion, and a flange portion which extends radially outwardly from one of opposite axial ends of an outer circumferential surface of the cylindrical portion. The cylindrical portion of each green end cap is inserted and positioned in a corresponding end portion of the green ceramic tubular body, such that the flange portion abuts on an end face of the corresponding end portion of the green ceramic tubular body.