Thanks to its high hardness and cracking resistance in hot-working operations, AISI H13 is acknowledged as all-around steel for die making in high-pressure die casting, extrusion, and hot stamping. In addition, the opportunities offered by Additive Manufacturing (AM) to fabricate complex shapes and closed channels strongly meet the needs of hot-work tools designers but typically are not easily exploitable. Indeed, the processability of martensitic steels such as AISI H13 by those AM technologies working at ambient temperature is challenging due to process-related thermal cracking susceptibility. Although several studies in the literature investigate the processability of this alloy by Laser Powder Bed Fusion (LPBF), the Electron Beam Melting (EBM) process has rarely been investigated. In this work, the microstructural characterization of an EBM-processed AISI H13 is presented through the correlation between the complex thermal history related to the EBM process and the as-built microstructure.