The demand for ROV operations has increased the last couple of decades. Still, operations are heavily dependent on an experienced ROV pilot, but by developing a sophisticated control system, operations can be performed with higher accuracy than before. In addition the need for constant supervision will be reduced. It is however important to acknowledge the fact that with increased level of automation, fault tolerance must follow in order to maintain the reliability. This thesis explore the various aspects development of a sophisticated computer-based control system involves. As an overview, this includes planning, implementation, and commissioning, as well as all the steps between. The development process utilized concepts from extreme programming in order to bring structure to the planning and implementation phase. The new structure of the control system use an Object-Oriented architecture in order to create a generic setup. Commissioning work is then limited to setup of a configuration file, and signal processing between the system and the ROV. Together with the control system, a user interface has been created. The user interface aims at making ROV operation more user-friendly, while at the same time include the more advanced features. Usability testing have been conducted on both the user interface and the control system. The control system has been tested in a sea trial with the ROV SF 30k. The results were promising even though it was the first time this type of a control system had been connected to and used on SF 30k.