More and more people begin to pay attention to how foodstuffs are produced. Due to the changing lifestyle, consumers seek products that do not require long preparation. The extrusion-cooking process responds to this type of applications with an easy management of processing promising product stability and quality. Extrusion-cooking involves the extruding of granular material under high pressure and high temperature. Such a method of treatment of raw materials makes extrudates produced from natural ingredients, i.e. corn or rice, suitable for direct consumption and guarantees their prolonged shelf-life. In our study, mixtures for instant grits were prepared from corn with a rice additive of 25% and 50%. Extrudates were prepared using a single-screw extruder TS-45 (L/D=12:1). The range of the temperatures of the extrusion process was 125/130/135°C. The process was carried out with the variable screw rotation speed of 80, 100 and 120rpm. This paper presents the results of process efficiency and energy consumption during the extrusion-cooking of instant corn-rice grits. Based on a bidirectional analysis of variance, the process efficiency, regression equation and correlation coefficients were determined for evaluating the impact of the processing conditions on selected properties.