Several scientific discourses influenced by ‘colonial discourses’ are reproducing discriminatory categories of human societies and are therefore incapable of deconstructing the ‘coloniality of power’, and grasping the complexity and interconnectivity of human societies. This makes decolonising of knowledge – including the knowledge base of international social work studies aiming to fight global inequalities – an urgent task of any critical research. Such a position urges the researcher to carefully choose research questions, methods and theoretical perspectives. Based on the authors’ own studies of global inequalities and critical reflection processes, this chapter explores that by using established scientific concepts and discourses in international social work, research runs the risk of legitimising and reinforcing global inequalities. It is argued that critical reflection as a decolonising research methodology can be helpful for finding alternative ways of doing research and collecting data when practising postcolonial intersectionality in international, national and local contexts. The chapter also discusses the importance of methodological concerns in international social work research, and how critical reflection guided by postcolonial perspectives can be used as part of a research methodology for studying social problems and global inequalities beyond South/North divides.