The paper explores various applications of authentic corpus language data in professional language classroom at university level. The research investigates opportunities provided by the freely available online corpus EcoLexicon, which is a visual thesaurus with a specific focus on the domain of Environment and is meant to facilitate environmental texts comprehension and generation. The authors consider possible limitations as well as potential of EcoLexicon for the professional language training of environmental sciences students. Traditionally professional language learners are exposed to extensive reading tasks interspersed with L2 webinars and lectures. However beneficial these activities are for the development of passive skills, such as listening and reading comprehension, none of them directly contribute to active production skills such as writing, speaking and L1/L2 translation. One of the key elements of successful professional speech production is accuracy, thus it is of specific importance to address potential pitfalls by designing teaching activities which involve translation and expose students to multiple examples of lexical items in context. This paper demonstrates pedagogical implications of EcoLexicon corpus in ESP curriculum of Environmental studies students and discusses rationale behind introducing corpus tools to non-linguistic students.