A wide variety of adhesive joints architectures is available, offering several options to the designers, although the most common are single-lap joints (SLJ), double-lap joints, and scarf joints. Additional designs, less used and studied are the stepped-lap, T-joints and tubular joints. T-joints find application in different types of industry, such as aircraft to bond stiffeners to skin and in the cars between the B-pillar and the rocker. This work numerically evaluates the performance of the structural adhesive Araldite® 2015 in an aluminum T-joint, after validation with experimental results. A cohesive zone modelling (CZM) numerical study is carried out to capture the behavior of different T-joints geometrical configurations when subjected to peel loads. The work includes a parametric study, considering maximum load (Pm) and dissipated energy at failure (U) prediction, considering four geometrical parameters: flat adherend thickness (a), T-element thickness (t), overlap length (l) and T-element radius (r). A significant effect on Pm was found for the tested parameters, and the CZM method revealed to be a precious method for studying T joints with precision and accuracy.