Written inquiries, which are more frequent and have less of a focus on complex thinking, are issues at school. Students are not taught how to respond to questions found in High-Level Thinking Skills (HOTS) tests, hence, their thinking abilities are generally weak. The issue for teachers is that neither they nor anyone else has been able to create evaluation tools for written HOTS. Therefore, the HOTS assessment instrument needs to be created. The goal of this study was to develop a written test instrument based on English material using the HOTS concept. The research and development (R&D) method was used to conduct an explorative and descriptive research using the five-stage Plomp model. The participants in this study were Senior High School Madani Alauddin Pao-Pao graduates from the 10th batch. The data was collected through documentation, interview guides, testing, and checklists for validation. Reading/remembering, describing, and categorizing were used as three qualitative data steps in the data analysis process. The validity, item analysis, reliability, difficulty, and clarity of the quantitative data were all examined by experts. The findings demonstrated that the test tool was highly valid, with an average HOTS test instrument score of 3.7. As a suggestion, teachers, educators, practitioners, and lecturers can use the HOTS test appropriately according to students' development to develop high-level thinking abilities in English writing.