In this paper I am trying to find which kind of L1 interference takes place in the pronunciation of certain English phonemes when Catalan speakers with an advanced level of English speak this language. Speakers of Central and Majorcan Catalan were asked to perform several production tasks and their pronunciation of words containing /d/, /D/, /b/ and /v/ was auditorily analysed. No significant difference was found between speech styles and results show that L2 speakers transfer their L1 phonemic inventories and the mapping from phones to allophones from L1. These findings have implications for second language phonology and speech production models.