In a process for producing a cathode for a cathode ray tube of directly heating type, which comprises shaping a heat-resistant and electro-conductive, flat metal plate, into a cathode substrate body having two leg pieces extended in the same direction and a flat part connected to one end of each leg piece, forming a heat-diffusible metal powder layer having a good affinity to said flat metal plate and on an outer surface of said flat part, heating the powder layer, thereby diffusion bonding the powder layer to the flat part and forming a bonding layer having an uneven surface, to which a thermionic emission layer is to be bonded, and forming the thermionic emission layer on the surface of the bonding layer, the process is characterized by forming on said flat metal plate a metal layer having a good affinity to the flat metal plate, by diffusion bonding, thereby forming a compound plate, and shaping the resulting compound plate into the shape of said cathode substrate body. A cathode having less thermal deformation and a longer life can be produced thereby.Furthermore, the process is characterized by applying a plastic working to the compound plate to a desired thickness and shaping the resulting compound plate into the shape of the cathode substrate body, and a cathode having much less thermal deformation and much longer life can be produced thereby.