Understanding the diffusion and trapping of hydrogen isotopes (HI) in plasma facing components (PFC) is an important issue for future fusion device operations. For such a purpose, specific macroscopic rate equations (MRE) codes were developed to solve both diffusion and full kinetic trapping of HI in metals, using the McNabb and Foster equation. Numerical simulations based on these codes have shown the important role played by temperature on HI inventory, so that a particular attention must be paid to the determination of the thermal field, especially for 2D geometry. Furthermore, the modification of the mechanical properties due to spatio-temporal temperature variation could impact the HI inventory. In order to understand the thermo-mechanical coupling, a special focus has to be made to develop numerical models which, beside HI transport and trapping, include the coupled resolution of the thermal and mechanical problem, for 2D and 3D complex geometries. In this work, we propose a fully coupled 3D MRE code, based on the generalized transport and trapping temporal equations, the heat equation, and the mechanical behaviour. The model is based on the 3DS Abaqus finite element software. This code basically solve the mechanical and the diffusion problem; using User Subroutines, a kinetic trapping, a transient multi-diffusion process and a thermal expansion effect have been added. Several simulations are then performed, dedicated to model the tritium diffusion and trapping through a port plug first wall of the ITER tokamak during Deuterium-Tritium (D-T) operations, made of a 316L stainless steel. Tritium retention predicted with the Abaqus code based on the 2D transient thermal field and trapping resolutions will be compared with the 1D equivalent case, and with less comprehensive thermal field (a steady state time-dependant temperature assumption) and trapping process (Oriani’s equilibrium assumption) resolution cases. Last, the role of thermal expansion will be discussed.