The paper describes existing requirements for tool materials. In the light of experience with these supplied materials, we have demonstrated their considerable influence on the life of molds for die casting technology. From this research came the evaluation methodology of these tool materials which has been used for directing the development of a new material. Based on the new regulation of the chemical composition a sample was casted and forged after that. Then was determined the process of heat treatment and from a block of this material a mold insert was produced. This insert is now being tested in production.