This paper presents a novel optimization method for the air- and gas-supply network comprising several air compression systems and air and gas streams in an industrial chemical plant. The optimization is based on the hybrid model developed by Han and Han for predicting the power consumption of a compression system. A constrained optimization problem was formulated to minimize the total electric power consumption of all the compression systems in the air- and gas-supply network under various operating constraints, and was solved using a successive quadratic optimization algorithm. The optimization approach was applied to an industrial terephthalic acid manufacturing plant to achieve about 10% reduction in the total electric power consumption under varying ambient conditions.