Abstract The fabrication of molds for injection molding of polymeric materials using 3D printing from tool steels is increasingly being considered due to its potential for higher productivity compared to conventional manufacturing processes. Understanding the mechanical and microstructural properties of these materials is essential for evaluating their application in tooling. This study investigates the mechanical and microstructural characteristics of H13 tool steel manufactured by the Atomic Diffusion Additive Manufacturing (ADAM) process, offering a novel approach to its additive manufacturing. H13 steel specimens were produced using a polymer binder mixed with metal powder and subsequently subjected to debinding and sintering. Hardness, tensile strength, surface roughness, optical microscopy, scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) were employed to characterize the material. The results showed a relatively uniform microhardness distribution among the analyzed orientations, with an average value of approximately 442.0 HV0.01. The material exhibited an ultimate tensile strength of approximately 1376.0 MPa, together with limited ductility. The as-printed surface presented relatively high roughness, while fracture analysis indicated a mixed ductile-brittle fracture mode. Microstructural characterization revealed relatively coarse grains, dispersed carbides, and a relatively homogeneous distribution of microstructural features and pores. EDS analysis indicated the presence of oxygen-containing inclusions. Overall, the results demonstrate the potential of the ADAM process for producing H13 tool steel components with relatively uniform mechanical properties, while highlighting surface roughness and internal defects as areas requiring attention in subsequent processing and applications.