Purpose: to present a new application for mobile devices, referred to as Desembaralhando, for intervention in the problem of dyslexic children mirror writring. Methods: the development of the application is the result of a set of clinical and speech therapy information and experiences, which points out frequency of letter mirroring as a challenging problem in children with dyslexia. The application, developed in the light of the multisensory approach, was created by a multidisciplinary team of computer scientists, a game designer and a speech therapist, in order to meet users requirements, such as appropriate fonts and colors. Results: the activities stimulate phonological awareness skills from the association between images and words, audio aids, as well as an original function that is the rotational movement of letters b/d and a/e, which facilitates the perception of the visual layout of the letters. Conclusions: guidelines such as the choice of typography and interface colors appropriate to dyslexic children are used to favor intervention, in order to minimize the difficulties of these children regarding letters mirroring.