Portal frames are the most commonly used structural forms for single-storey industrial structures. For structures of this type, an unsuitable layout plan can increase total cost of construction; hence a suitable layout plan is of importance to achieve an economical design. This may require several trial designs. The optimization study presented here examines some key geometric and material parameters of industrial portal frame structures with different over head cranes capacities. The key parameters considered herein are: span of portal frame, portal frame spacing, overhead crane capacity and material properties of the single and double bay portal frames. The internal forces and deflections are calculated under the applicable gravity (considering the action of both crane and its load) by using elastic first-order static analyses, utilizing the finite element method. The current study examines the function of each of the above-mentioned parameters and presents the optimum parameters in terms of weight per unit area of portal frame. The results are presented in graphical form suitable for the preliminary stages of design of industrial portal frame structures with overhead cranes.