In this paper, economic criterion based on products market values is utilized as an objective function for economic optimization of steam-cracker operation. Established generalized approach is applied on specific facility in Litvinov ethylene production unit (Unipetrol RPA). Optimal processing conditions are searched for several selected gasoline feedstock. Sensitivity of optimums on individual products prices was investigated. The possibility of separate cracking in the contrast to the cracking of blend was considered and analysed with respect to current product prices.