Given the limited time for instruction in the classroom, pronunciation often ends up as the most neglected aspect of language teaching. However, in cases when the learner's pronunciation is expected to be good or native-like, as is expected of language teacher trainees, out-of-class self-study options become prominent. This study aimed to investigate the effectiveness of online text-to-speech tools used by EFL teacher trainees when preparing for an oral achievement test. The study was conducted with 43 junior year teacher trainees at a large state university in Turkey. A pre- and post-test experimental design was used. Both qualitative and quantitative data were collected through a questionnaire to explore the trainees' opinions related to pronunciation and their practices to improve this, a post reflection questionnaire for the effectiveness of the procedure, and a speaking rubric to evaluate the oral presentations of the trainees. The results indicate that the trainees perceived a native-like accent as a measure of being a good language teacher. It was also revealed that text-to-speech websites are effective self-study tools in improving trainees' pronunciation.