Abstract: In the present days, English communication becomes the international mass connection between people and organizations. The crucial barriers of the English communication would be low level of competency especially for non-native speakers. Developing language profiles of graduates for higher levels of speaking skills to serve the need of workplace in Asian Economic Communities becomes a high concern in many countries including Thailand as one of the providing strategies for ASEAN association. This study investigated and identified levels of English oral communication competency of civil engineering students at a Thai university of Technology with the proposing designed instrument based on the ESP theory aiming to search for specific points for further development. The informants were assessed with tasks composed of structured interviews with pictures to draw out the linguistic features in specific work context using the constructed rubrics. Finding revealed that the participants were ranged at the average level and their significant English oral competency deficiencies fall on grammatical errors and pronunciation and the use of L1 to communicate. However, the interaction aspect indicated that the students are able to interact and communicate in the specific work context if they have the technical content schema. To estimate the proposing tools, results revealed that the first set of the instrument used for signifying levels of English competency of the informants and the second set with scoring process and rubric evaluation to assess the students’ English performance noted in the first set appeared the reliability. Data from this research is used for implications and recommendations for developing the quality of Thai engineers.