As interest in high-temperature electrochemical devices such as solid oxide fuel cells (SOFC's) has increased, there have been tremendous needs to develop an appropriate joining technique, which provides hermetic seal and proper strength under operating conditions. A recently developed technique referred to as reactive air brazing (RAB) has shown a promise in the joining of components used in high-temperature applications. Similar to active metal brazing technique, the reactive component in the RAB is reactively to modify oxide faying surfaces, improving the wettability with the oxide and potentially increasing bond strenth between braze and ceramics. The most important advantage of RAB over conventional active metal brazing is that joining operation of RAB technique can be conducted in oxidizing atmosphere since oxide is used as reactive species. In this paper, properties and microstructure of these brazes will be discussed.