Disclosed herein is a cooking appliance having an improved cooling mechanism. The cooking appliance includes a first cavity forming a first cooking chamber and a second cavity forming a second cooking chamber, and has a cooling mechanism for cooling both the first cavity and the second cavity. A separate third cooling channel is formed to exhaust air from the first cooking chamber. A vent for the first and second cavities may be formed at a lower portion of the second cavity such that air may be exhausted via the vent.