The purpose of the conducted research was the development of mobile accessibility design guidelines focused on the needs of older users. In order to achieve that purpose, the current sets of accessibility guidelines were analyzed and compared. Also, the set of guidelines that provides better support to implement and/or increase mobile accessibility was identified: the set developed by W3C. Subsequently, the current sets of accessibility guidelines were unified as a preamble to the development of a standard, which is out of the reach of this thesis. Next, an experiment was designed, it included the conducting of usability tests, whose results allowed the development of mobile accessibility design guidelines. Finally, it is important to highlight that a new methodology to develop mobile accessibility guidelines was created.