Protein rich extruded products were prepared from locally available and low cost raw materials different blends of lupin and whole grain maize flour using a twin-screw extruder. The extrusion effects on the physical, functional and proximate properties of the extruded product were evaluated as related to the different process variables. The variables includes blending ratio (10-20%), barrel temperature (120-150°C) and feed moisture content (1418%). A three-factor, three-level Box-Behnken design (BBD) and response surfaces plot that served to evaluate the significance of independent, interaction and quadratic effects of extrusion process variables. Second order polynomial regression equations were developed to relate the product responses to blending ratio and process variables as well as to obtain the response surfaces plots. The independent variables (Blending ratio, Barrel Temperature, and feed moisture content) had significant (p ≤ 0.05) effects on physical and functional properties of extruded products. Higher blending ratio increased the bulk density and water solubility index, but decreased the expansion ratio, and water absorption index. Higher feed moisture content decreased the ER and WSI values, whereas higher feed moisture content increased BD and WAI. Higher barrel temperatures increased expansion ratio, but decreased the bulk density. In this work, the proximate compositions of the extruded material considered were product moisture content, protein content, fat, crude fiber, ash, and carbohydrate content. All these properties were significantly (P ≤ 0.05) affected by the process variables. ANOVA analysis indicated that extrudate moisture content was influenced by blending ratio and feed moisture content, protein content by linear and quadratic terms of blending ratio, fat content by linear and quadratic terms of blending ratio, (barrel temperature*feed moisture), and quadratic terms of barrel temperature, fiber, ash and starch content by blending ratio at p≤0.05. Sensory analysis was conducted using a semi trained panelists. Optimized extrusion parameters for preparation of snacks were blending ratio of 15.0611 (%), barrel temperature of 150 (°C) and feed moisture of 14.00 (%) having desirability value of 72.8%. Future research is required on the scale-up of the optimized formulation and process identified in the present study.