This exploratory qualitative study aims to explore the ChatGPT use of Van-Lang-University graduate students in a research writing course and the cognitive levels of their reactions to its responses. The data was collected from observations and interviews with twelve Vietnamese graduate students studying in a research writing class at this university. According to the findings, the participants opted for ChatGPT as a help-seeking strategy during their course due to several reasons including its convenience, instant feedback, and multifunction. Additionally, they had critical reactions to ChatGPT's feedback and advocated that ChatGPT could not replace lecturers' roles in future language classrooms. To develop the growth of critical ChatGPT use for research writing in Master's programs in English Language Studies at Van Lang University, actions from relevant stakeholders is required, including policymakers, lecturers teaching research writing, and MA students. [This chapter was published in: "Implementing AI Tools for Language Teaching and Learning," edited by Vu Phi Ho Pham, Andrew Lian, Ania Lian, and Sandro R. Barros, IGI Global Scientific Publishing, 2025, pp. 199-224.]