This study aims at investigating the problems encounter (ESP) students in using English prepositions of time (on - at - in). It also sheds light on the causes stand behind these problems. The study adopted a descriptive, analytical and quasi-experimental method. The sample of the study consisted of (40) students at Posha Academe in the first semester of the academic year 2017 - 2018. To collect data, the researcher employed a test. The study used (SPSS) to analyze the data. The findings revealed that the majority of the students encounter problems in using prepositions of time.

Based on the findings the study offers the following recommendations: Curricula designers should pay more attention for prepositions in designing syllabuses .Teachers should deliver intensive exercises to students concerning prepositions. Students should give more attention to English in general and prepositions in particular. Teacher should employ effective teaching techniques to help students improve in this area.