The understanding of the human brain functions and the underlying processes has long been concerned with humanity. It became easier due to the development of electronics and medical sciences, thus there are more sophisticated devices and methods available. Beyond medical sciences, the consumer electronics industry shows increasing interest in discovering brain processes with non invasive methods. After the millenium more and more portable BCI (Brain-Computer Interface) devices were introduced based on EEG method, with which the electrical signals of brain activity can be measured on the scalp, without disturbing the user of the device. Due to the portable design of BCI devices, in the medical practice the continous monitoring of mental illnesses (eg.: epilepsy), in entertainment industry the control of our casual devices (eg.: mouse cursor control), in advertising industry the measurement of the efficiency of advertisements become possible. The purpose of this thesis is to learn about and present the available technologies and portable devices available on the market for brain monitoring and the implementation of a prototype of a Brain-Computer Interface with the lowest possible budget.