In this work we report an analysis on Ni/4H-SiC interfaces aimed at optimizing the ohmic contacts. Several thermal cycles have been performed by rapid thermal annealing checking the possible chemical reactions at the metal semiconductor interfaces. Micro x-ray diffraction and micro Raman techniques have been performed in order to study the interface micro structural evolution. Inter diffusion of each element at the Ni - SiC interface was examined using Auger spectroscopy. Electrical measurements have been performed in order to check the ohmic behavior of the contacts. Finally, a correlation between microstructures evolution and electrical behaviors is reported.