For high school students in the Middle East, academic writing plays an increasingly important role, particularly for those planning to pursue higher education in English-medium universities where assessments such as IELTS and TOEFL reflect international academic expectations. Against this background, the present qualitative study examined students’ use of cohesive devices and explored the challenges they face in producing clear and coherent academic writing. The study consisted of ten high school students who participated in a pilot project and completed a researcher-designed diagnostic writing task under real-time classroom conditions. Observations, open-ended questionnaires, and semi-structured interviews were used to compile data, allowing a comprehensive study of students’ writing practices, experiences, and obstacles. Manual analysis of the writings revealed common cohesion (e.g., references, substitutions, conjunctions, and collocations) and coherence (e.g., logical organisation and usage of linkers) flaws. Results exposed regular problems with grammatical and lexical coherence as well as inadequate arrangement to present concepts. In order to raise students’ awareness of coherent and logical writing styles, boosting their academic and professional success, teachers have to focus on targeted instruction and feedback strategies.