In this study, the characterization of metal-ceramic interface was investigated. For the characterization, original opaque porcelain powder was applied on metal crown at three different temperatures and in three different times. To examine the occurrence at the interface of the metal-ceramic diffusion couple and the effects of the firing temperature and vacuumless waiting time, 9 samples were prepared by 3 different firing temperatures (905 degreesC, 930 degreesC, 955 degreesC) and 3 different times (30 s, 60 s, 90 s) in a vacuuinless condition. During the firing process, the samples were exposed to vacuum. When the furnace was heated to the sintering temperature, vacuum was turned off and the samples were kept in this condition for 30 s, 60 s and 90 s. The interfaces of metal-ceramic diffusion couples that were occurred after firing were prepared for the EPMA investigation. According to the concentration profiles, diffusion coefficients of Ni and Cr in porcelain and their activation energies were calculated. As a result it was seen that, when metal-ceramic composite was exposed to heat, an atomic diffusion occurs between them.