In-situ experiments on the Ni/SiC interface reaction were carried out with a high temperature X-ray diffractometer capable of measuring the X-ray diffraction pattern in 1-2 s using an imaging plate. The kinetic formation processes of the interface reaction layer were measured in short-period exposure experiments with the apparatus. The time-temperature phase diagram of Ni/SiC in N-2 was determined. delta-Ni2Si and theta-Ni2Si (high temperature phase of delta-Ni2Si) were formed at the Ni/SiC interface between 1072 K and 1418 K in N-2. The formation of delta-Ni2Si obeyed the parabolic rate law. The value of the activation energy suggests that the diffusion of Ni through delta-Ni2Si controls the rate of formation, The results of thermal expansion coefficient measurements suggest that when a sample is cooled to room temperature, compression caused by delta-Ni2Si occurs on SiC.