The aim of this research is to explore a possible method for identifying an alphanumeric character produced by an individual with motor and vocal disabilities and whose possibilities to interact with the surrounding environment are limited to the movement of the face. The reason behind the creation of an alphanumeric character interpretation algorithm is linked to the fact that attempts to use existing algorithms (such as Tesseract) gave poor results in this scenario. The reason of the low success rate was not investigated; the focus was on finding a functional solution to the objective. Obviously subsequent studies in this sense are desirable. A Human-Computer Interaction algorithm has been developed in order to allow a person with limited mobility to interact with a computer, to which commands can be given.  This project is based on three main elements: the identification of facial parameters, their tracking and the interpretation of the word expressed. A Linux based Python application has been coded to elaborate information from a camera. The main action is to identify the face of the potential user, activate tracking when the subject closes his eyes for a defined numbers of times, then follow the trajectory of a point of the face (in our case the tip of the nose), interpret the letter thus drawn, buffer the letters and finally convey the command (entire word) thus obtained. At the end, statistics on the success percentage are provided.