A convection oven having one or more intermediate air plenums is disclosed. An intermediate air plenum placed within an oven cavity defines the bottom of an upper cooking chamber and the top of a lower cooking chamber. Each intermediate air plenum comprises a left side air inlet for receiving heated air from a left side air channel located on a left side cavity wall of the oven cavity, a right side air inlet for receiving heated air from a right side air channel located on a right side cavity wall of the oven cavity, a top plenum surface including a plurality of top air outlets configured to direct a portion of the heated air upwards, and a bottom plenum surface including a plurality of bottom air outlets configured to direct a portion of the heated air downwards. The top and bottom plenum surfaces are preferably shaped to optimize even distribution of heated air flow into the oven cavity.
