For neural applications, materials that combine excellent electromechanical properties with long-term (> 5 years) and high fidelity performance capabilities have not yet been reported. Good electrodes should not only be able to adapt to eventual physiological changes in the body (e.g. inflammatory responses), but also able to perform without damaging the host tissue. The combination of these two characteristics is difficult to accomplish, because the ability of a material to undergo changes is often accompanied by the formation of reaction products that might interact with the surrounding tissue, and eventually harm it. Glassy carbon is a biocompatible and electrochemically inert material with tunable mechanical and electrical properties, high charge injection capacity and great resistance to corrosion. These merits motivate the use of glassy carbon for neural applications, and in particular for the realization of electrocorticography (ECoG) microelectrodes that can sense and stimulate brain activity.  Thus we propose to replace the commonly used noble metals like platinum, gold and iridium, with glassy carbon to improve the performances of traditional neural prostheses, thanks to better charge transfer capabilities and higher electrochemical stability. This investigation specifically reports characterization of glassy carbon microelectrode arrays (MEAs) used to sense and stimulate neural activity. Further, we report on key findings in long-term effects based on histological analysis of the brain tissue after chronic implants. Significant focus is given in this work to the investigation of tissue responses of motor cortex after 6 weeks of implantation, and to materials degradation of chronic in-vivo implants. In-vivo long-term impedance measurements and brain activity recordings are also performed to test the functionality of the neural devices and reported here.