Before leaving to Vila Nova de Gaia, international students are advised to follow an Intensive Portuguese Language Course, although this is not a pre-requisite.
The most study programmes contents of ISPGAYA courses are taught in Portuguese (Content and Language Integrated Learning (CLIL)), where international students are integrated. Moreover, learning a foreign language is one of the biggest advantages of mobility programmes. In addition, it is also a great opportunity to learn one of the ten most spoken European languages - PORTUGUESE - in the world (with about 200 million speakers).
Meanwhile, the available offer by Portuguese HEI is advertised in http://www.proalv.pt/wordpress/erasmus-2/ [1]
Links:
[1] http://www.proalv.pt/wordpress/erasmus-2/