Copper and sol-gel processed cordierite were cosintered in oxidizing atmosphere using an eutectic bonding technique. Firing at low and high heating rates leads to interfaces which present different macroscopic properties. These interfaces were therefore investigated on a microscopic scale by SEM, XPS and STEM analyses. Copper diffusion as well as strong chemical and structural modifications were observed in the interface region. Although these interfaces have good adhesion properties, there was no evidence for the formation of some interfacial copper compound.