Mn_xCr_3-xO₄ spinels have electrical conductivity of from 4x10^-3 to 0.4 W.cm^-1 at 800 °C depending on the ratio of Mn/Cr. They are potential coating materials on Fe-base and Ni-base interconnect alloys because of their stability in both reducing and oxidizing environments and low evaporation rate of Cr-species. In this paper, the interaction between Mn_1.5Cr_1.5O₄ and different cathode materials such as La_0.8Sr_0.2MnO₃ (LSM), La_0.8Sr_0.2CoO₃ (LSC) and La_0.8Sr_0.2FeO₃ (LSF) were carefully studied using XRD, SEM, EDS and other techniques. Three different approaches were used for this study. First, powders with all elements from spinel phase and perovskite phase at the appropriate ratio were made through a glycine nitrate process (GNP). These powders were calcined at 1200 °C for 4 h, and then X-ray diffraction was conducted to determine the most stable phase formed. Secondly, the powders of spinel and different cathode materials were mixed and pelletized, and then calcined for variable durations. X-ray diffraction results indicated that only spinel and perovskite phases were formed. Careful investigation of the positions of the XRD peaks revealed small shifts of the peaks, which were caused by the interdiffusion of the cations in the two phases. Thirdly, mated surfaces were produced to more quantitatively determine the diffusion behaviors at 1200 °C for different cathode materials. A model was set up to explain and also predict the diffusion between these two phases. The compatibility of the spinel with different SOFC cathode materials was discussed in light of the experimental results.