The main purpose of this research is to investigate the effectiveness of on-line game Kahoot on technical vocabulary learning and motivation among preparatory year engineering students. To achieve the purpose of the study, a pre- post-test was constructed to measure students' level in technical vocabulary learning and a questionnaire to measure the students' motivation towards learning technical vocabulary. The participants of the study, totaling 60 divided into two groups (experimental and control), were selected from AL Salam Higher Institute for Engineering and Technology during the second semester of the academic year 2019/2020. Both the control group and experimental group received their lectures online. In addition, the experimental group used the on –line game Kahoot to do extra quizzes on technical vocabulary. Independent T. test was used to analyze the results of the study. The findings of the study indicated that there were statistically significant differences in the post- test and post questionnaire between the control and the experimental groups in favor of the experimental group. In addition, there were statistically significant differences between the results of the pre- and post-test and questionnaire of the experimental group in favor of posttest and questionnaire. These findings revealed that the on-line game Kahoot had a positive effectiveness on the students' technical vocabulary learning and their motivation towards learning technical vocabulary.