Thermo-inductive testing is a new technique used for health investigations on different components of automotive and aeronautic industries. In this technique, eddy current deviation around the default creates local heating which can be detected by an infrared camera. The purpose of this work is to develop a 3-D finite-element model as a support tool to study the reliability of the technique. To reduce the number of unknowns, shell elements are introduced to model defects or thin conductive regions. Inspected materials are classified into metallic and composites. Investigations on various parameters of the technique and crack dimensions are performed in order to optimize the method. Experimental and simulation results show that the method is well suited.