Abstract.To determine the hydrogen-embrittlement resistance of anchor rods in the new San Francisco-Oakland Bay Bridge, tensile tests of full-size ASTM A354 Grade BD anchor rods were conducted at very slow load rates. Resistance to embrittlement by hydrogen entering the rods while under load, also referred to as stress corrosion cracking (SCC) or environmental hydrogen embrittlement (EHE), was measured by performing the slow-load tests in 3.5% sodium chloride (NaCl) solution. Resistance to embrittlement by hydrogen entering the steel during fabrication processes such as hot-dip galvanizing, also referred to as internal hydrogen embrittlement (IHE), was measured by performing the slow-load tests in air. Testing was conducted on rods representing various sizes, different manufacturers, rolled and cut threads, different alloys, as well as galvanized and ungalvanized rods. Following slow-load hydrogen embrittlement tests, mechanical and chemical properties of the test rods were fully characterized, and fracture surfaces were examined by scanning electron and optical microscopy to establish modes of failure. The results of this work are discussed in terms of 1) material properties, such as strength level and hardness, and toughness; 2) processing variables, including galvanizing, and threading method; 3) the cause of failure of 32 anchor rods in March, 2013; and 4) establishment of safe loads for rods currently in service on the bridge.