With the objective of being able to do an optic link between two CubeSats, a low cost attitude control system is studied and designed. The system requirements are set by the Electronics Department of the Universitat Politècnica de Catalunya, who fixed a combination of micro-controller, driver and motors that should suit with the needs of the project. With the objective of keeping it very low cost, the motor studied is a recycled motor from an HDD (Hard DriveDisk).The current state of the art in attitude control systems for CubeSats is studied and a decision is made regarding the needed components of our low cost system.The kinematic and dynamic equations of the system are determined and the reaction wheel ismodeled as simple as possible to develop a control law system for the CubeSat. An open-loop and closed-loop model are tested to prove their stability.In order to test our hardware, the driver is studied to identify all the different parameters that can be modified and the computer is set with the appropriate programs to be able to communicate with the driver. The motor specific parameters like the motor speed constant and the resistance are found and correctly set in the drivers to successfully run the motor at full speed.