The Ni-rich Ni-Ti system has been studied by many researchers using many different techniques. The mentioned studies have concluded that cuboidal-type γ´ precipitates are the cause of hardening, but these precipitates coarsen at high-temperature and prolonged service time causing loss of coherency and eventually affect the mechanical properties. Coarsening is theoretically described by the model proposed by Lifshitz-Slyozov and Wagner (LSW theory) [1, 2] which predicts precipitates dispersed in a fluid matrix that coarsen according to the relationship, r3 = krt. A different behavior of kr during the coarsening has been reported for Ni-based alloys with elastic strains, where kr decreases in function of increasing fv, which is known as anomalous coarsening [3, 4]. A more realistic model, where coarsening is independent fv, has been developed by Ardell and Ozolins [5] and Ardell [6] and is called trans-interface diffusion-controlled (TIDC) theory. A rate law of type <r>n ≈ kIt is predicted by the TIDC theory. On the other hand, Miyazaki [7] proposed a novel microstructural characterization method to study the precipitation process in binary alloys, called the macroscopic concentration gradient (MCG) method. It is based on the microstructural observation of different composition alloys formed by a continuous composition gradient. The purpose of this work is to analyze the coarsening of γ´ precipitates in Ni-rich Ni-Ti alloys using a composition gradient generated by diffusion couples in order to determine which model, LSW or TICD, fits better.