Quadratic control synthesis methods are applied for designing a coupled proportional-plus-integral controller for a reforming furnace. Temperatures are controlled in five catalyst tube ranks by regulating the fuel in six burner ranks. The plant model is devised to match open loop data on an operating furnace. The model contains parameters representing the plant's temperature response time, radiation coupling between tube ranks, and fuel heat value. Evaluation criteria are rms responses to stochastic disturbances of temperature rate, closed loop pole locations, and transient responses to step disturbances. The controller provides fast but well damped responses without excessive fuel regulator action. Its robustness is demonstrated by successful control for off design plants.