A cooking oven with an air diffuser disposed in the oven cavity to diffuse circulating air prior to entering an air inlet to a fan. The oven cavity comprises a wall with the air inlet aligned with the fan that draws the circulating air from the oven cavity. The air diffuser is installed in front of the wall and diffuses the circulating air evenly across food in the oven cavity and into the fan return without reducing an overall mass flow rate of the air.