Despite the growing interest in using online quizzes with Student Response System (SRS) for assessment, knowledge and empirical evidence about learner acceptance and risk of cheating are still limited in the literature. Hence, to address such gaps, this study explored Thai EFL learner acceptance and perceived risk of cheating of using Socrative for vocabulary tests. The participants (N = 461, 77.4% female, 22.6% male) attended a General English (GE) course that required them to learn fifty English words every week. The vocabulary tests took place in the first ten minutes of the class for ten weeks delivered by using Socrative. At the end of the course, this study investigated learner acceptance and perceived risk of cheating using a set of survey constructed based on Davis (1989) and collected the data of vocabulary learning outcomes and proficiency levels. The data were, then, analysed by using independent t-test, correlation, and multiple regression analyses. The results indicated Thai EFL learner acceptance of Socrative with the risk of cheating during vocabulary tests. Learner acceptance was influenced by proficiency level and predicted a small amount of learning outcomes. These results have some implications for instructional course designs adopting online quizzes for testing.