The growth of English into a lingua franca has inevitably created linguistic deviations and innovations in the use of English. These emerging uses that result from the needs and preferences of speakers whose mother tongues are all different can be broadly identified as lexico-grammatical and pronunciation features and they compose one of the main arteries of study in English as lingua franca communication. In an effort to investigate shared and systematized uses of English as a lingua franca (ELF) and their possible codification have formed the focus of considerable research in the field. This paper introduces an ELF corpus, Corpus IST-Erasmus, which is compiled as part of a PhD study to investigate the lexico-grammar of ELF interactions. The corpus consists of 10 hours 47 minutes of recorded speech and 93,913 words of transcribed data. It is compiled by means of 54 speech events, 29 interviews and 25 focus group meetings. The participants of the study are 79 incoming Erasmus students, representing 24 first languages. These languages are namely Arabic, Azerbaijan, Basque, Bulgarian, Cantonese, Chinese, Czech, Danish, Dutch, French, Galician, German, Greek, Italian, Korean, Lithuanian, Mandarin Chinese, Polish, Portuguese, Slovak, Spanish, Suriname, Turkish, and Ukrainian. The focus of this paper is to examine whether there are variations from standard English as Native Language (ENL) forms with respect to the use of prepositions in spoken ELF interactions, as have been outlined in ELF research (Seidlhofer, 2004). The paper also aims to present the emerging patterns in the use of prepositions and suggest implications for an ELF-aware pedagogy in English Language Teaching. Although there is an increase in the number of empirical studies, there is still a gap in the description of ELF discourse. In order to fully identify the characteristics of ELF, more corpora studies should be conducted. These studies will provide data for ELT professionals in designing an ELF-oriented pedagogy and materials. Besides, there is limited research on the English use of international students- none in the Turkish setting. The present research, therefore, aims to fulfil this niche in the ELF research.