SciEsp is a tool for scientific writing in Spanish. Its objective is to help students when writing abstracts of scientific texts, such as a thesis or a dissertation. The tool identifies the different components of an abstract structure according to the guidelines of “good writing” proposed by the literature. Each sentence in the abstract is classified to one of six different rhetorical categories (background, gap, purpose, methodology, result, or conclusion), warning the writer of a possible missing component of the “optimal” structure. We manually annotated a corpus of abstracts from computer science theses and dissertations, and use it to train a Naive Bayes classifier that achieves an F1-measure of 0.65. We expect that SciEsp becomes a starting point for further projects in the area of supporting technologies for scientific writing in Spanish.