A 718 superalloy, presenting a standard microstructure, was mechanically tested under uniaxial tensile loading at 80 degrees C and 300 degrees C in Light Water Reactor environment after an exposure at 300 degrees C for 200 h. Hydrogen embrittlement mechanism was clearly observed. In order to identify the most influent metallurgical parameters on hydrogen embrittlement, three "model" microstructures were synthesized to test the efficiency of carbides, delta, gamma' and gamma" precipitates to trap hydrogen at different temperatures. Results showed that gamma' and gamma" played the major role on the hydrogen embrittlement susceptibility of the alloy even though carbides and delta precipitates could also act as hydrogen traps and influence the final rupture mechanism. Results also characterized the influence of temperature on the fracture modes. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.