Catalan students may offer Catalan, but also Occitan and Spanish (which are also official languages in Catalonia), as long as they are fluent enough in these latter languages, and foreign students may offer their mother tongue or tongues in exchange. All languages are welcome, not only widespread national languages, but also the so-called regional or minority languages!
When pairing up tandems, however, absolute priority is given to those tandems in which Catalan is one of the two languages involved.
If you are a native Spanish-speaking student interested in learning Catalan, please e-mail us at voluntariat.linguistic@upf.edu and we will do our best to assign you a Catalan student who will introduce you to the national language of Catalonia.