This paper presents an innovative approach to controller design, and applies it to the pH-control problem. The proposed approach uses a robust controller implemented with a full two-degeee-of-freedom (2-DoF) structure. The first or "feedback" DoF was designed using a standard mu-synthesis approach A procedure based on a novel variation of l(1)-optimal control theory is applied to design the second or "open loop" DoF. This design may be carried out completely independently of the first DoF, provided an appropriate factorization of the feedback controller is used. The approach is illustrated by the design and evaluation of a control system for a laboratory scale pH-control plant. The resulting controller was implemented and tested on the physical plant. It was found that it gave good performance over widely varying conditions. Specifically, the open loop properties of the mu-synthesis feedback controller acting on its own, were improved significantly by the use of a certain class of l(1)-optimal second DoF controller block We conclude that the tradeoff between good command tracking and reasonable plant inputs given by a feedback controller can be improved by the use of the proposed approach, a novel variation on l(1)-optimization applied to the second DoF controller block.