The use of Mobile Devices (MD) is part of our diary life. People are used to use the MDs almost every day to communicate and collaborate with friends or colleagues in different environments such as work or education among others. This paper is focused on the use of this technology for collaborative learning contexts or Computer Supported Collaborative Learning (CSCL) environments. There are different tools which support CSCL like blogs, wikis or chats. However, most of the CSCL tools used present accessibility barriers which provoke that many people cannot use these useful learning tools. In concrete, this paper is focused on eliciting requirements for the design of an accessible chat as a synchronous CSCL tool for MDs in an accessible way. To achieve it, some guidelines and standards are considered as a reference to determine the requirements that a chat should have to be accessible. Moreover, the Scenario and Personas techniques are used to elicit the requirements from the point of view of users and using a User Centered Design (UCD) approach.