Although Computer Assisted Language Learning seems to gain in popularity among foreign language learners, Mobile Assisted Language Learning seems a field that not many learners prefer, mainly because of the inconvenience of the small screen and keyboard. But because of their ubiquitousness, mobiles can play a decisive role to language acquisition, especially regarding skills that do not require extensive use of keyboard. On this paper a study on foreign language learners will be described relative to the acquisition and retention of vocabulary via a mobile application. The application consists of two parts; the first is a brief podcast. During the podcast and whenever a new word is transmitted (chosen according to the class's syllabus), the written word and its image will appear on the screen. After the end of the podcast the learner will have to answer a multiple choice quiz with the new words. In this way the acquisition will be tested and in order to test the retention the same test will be repeated every next week. The multimodality of the mean is expected to help the learner remember new vocabulary. In order to control the efficacy of the application, another group of students will be studying the same vocabulary in traditional ways, given on a list or on their workbook. At the end of the study, which is expected to last four weeks, the first group will fill a questionnaire whose results will investigate their attitudes towards the method they used and the general use of multimodal applications via mobile for vocabulary acquisition and retention.