A heat recovery steam generation system (10) is provided. The heat recovery steam generation system includes at least one superheater (60, 62) or reheater in a steam path for receiving a steam flow and configured to produce a superheated steam flow. The system also includes an inter-stage attemperator (64) for injecting an attemperation fluid into the steam path. The system further includes a control valve (68) coupled to the inter-stage attemperator (64). The control valve (68) is configured to control flow of attemperation fluid to the inter stage attemperator (64). The system also includes a controller (66) coupled to the control valve (68) and the inter-stage attemperator (64). The controller (66) further includes a feedforward controller (92) and a trimming feedback controller (96). The feedforward controller (92) is configured to determine a desired amount of flow of the attemperation fluid and the trimming feedback controller (96) is configured to compensate for inaccuracies in the determined amount of flow of the attemperation fluid to determine a net desired amount of flow of attemperation fluid through the control valve (68) into an inlet of the inter-stage attemperator (64) based upon an outlet temperature of steam from the superheater (62). The controller (66) also determines a control valve demand based upon the flow to valve characteristics. The controller (66) further manipulates the control valve (68) of the inter-stage attemperator (64), and injects the desired amount of attemeration flow via the inter-stage attemperator (64) to perform attemperation upstream of an inlet into the superheater (62).