Abstract
This paper presents a comparative study between auxiliary verb constructions in (European) Portuguese (PT) and in (Peninsular) Spanish (ES), such as PT: O Pedro está lendo o livro/ES: Pedro está leyendo el libro ‘Pedro is reading the book’. We analyzed 98 Portuguese auxiliary verb constructions and 93 Spanish ones. The results showed a few matches and mismatches between both languages. The lexical mismatches watched can contribute to consider the nature of auxiliary verb constructions in both languages and their uses as foreign languages. Also, some relevant conclusions are provided for translators and other natural language processing applications.