Corn semolina and oat components (dehulled oat, oat bran and naked oat) were processed on a single screw extrusion-cooker S-45 (L:D=12:1). The investigations concerned the influence of the rate of oat components, moisture content of the raw materials, temperature, the compression ratio of the screw on the extrusion cooking process, physical and chemical properties of the extrudate as well. The die diameter and the screw speed were determined on the results on our previous research That properties were mainly tested, which influence application of the product as a food snack. With the great care were measured: radial expansion ratio, the specific density, the output of the extrusion-cooker, WAI and its influence on the texture. Extrusion-cooking of com-oat mixtures allowed to obtain a very good quality snack product, with a very good texture, with oat rate up to 20%. Oat components, mainly naked oat STM 3997 and STM 4097, could be recommended as the best one component for cereals snack production.