Tesis para optar al grado de Magíster en Lingüística mención Lengua Inglesa / Tesis no disponible en línea / The objectives of this research include the characterization of the lexicogrammar of hotel reviews and its relation with the Appraisal Theory (Martin and White 2005). The focus is put on the ‘affect’ and ‘orientation’ subcategories of such theory. This research is a first approach to an automated analysis of sentiment in large corpora, reason why the corpus consisted of 800 reviews taken from a website; 400 negative reviews and 400 positive reviews. This had the objective of finding out whether there were differences in the way each polarity or orientation was conveyed. The results show a relation with the Appraisal Theory’s categories mentioned, although there is no difference in the way negative and positive sentiments are expressed. In terms of lexical items, however, there is a difference in the use of modal verbs, which are found in a slightly larger quantity in negative reviews. The evaluative structures proposed by Hunston and Sinclair (2000) served as a database from which to start, however, they were not found as pervasively in the texts as expected. On the contrary, a whole set of new structures seems to arise from this research. Future applications of the findings of this research include the creation of computer-based platforms that may detect evaluation automatically, thus helping the identification of the needs of customers, not only of hotels, but of different kinds of services.