The study aims to determine the effects of translation apps on English vocabulary mastery of high school students. The method of this study was a Pre-Experimental design that consisted of one experimental class. The samples in this study were XII MIA SETIA students from SMAN 25 BONE. Samples were selected using a cluster random sampling technique with a total number of 17 students. The instrument for collecting data was Pre-test and Post-test. Based on calculations, the mean scores of post-test in the experimental class was 87.5. The results of the statistical hypothesis test using the paired sample t-test revealed the probability/significance level is less than the alpha level. Thus, the use of google translate has a positive effect on high school students English vocabulary mastery. Keywords— Vocabulary, Google Translate Application.