ABSTRACT The 253MA stainless steel fabricated via wire arc additive manufacturing displays a mixed austenite and ferrite microstructure. It features many dislocations, minimal inclusions, and carbides, observed through TEM. Notably, CeO2 spherical inclusions enhance its high–temperature and oxidation resistance. Microhardness test 2 shows average values of 187.9 HV0.2 and 183.9 HV0.2 in transverse and longitudinal directions, respectively. Mechanical properties at room temperature include a yield strength of 388 MPa, a tensile strength of 681 MPa, 18.89% elongation, and 34% area reduction post–fracture. Impact toughness measured 89.7J and 133.7J in transverse and longitudinal directions, respectively. At 600°C, the steel's yield strength and tensile strength drop to 208 MPa and 412 MPa, with elongation increasing to 32.06% and area reduction to 53%. The stress–strain curve at 600°C shows serrated flow, suggesting dynamic strain ageing. SEM analysis indicates ductile fracture with larger dimples at elevated temperatures.