Critical thinking is often understood as a set of tangible, transferrable and measurable skills and competencies. Yet, it is also an intensely affective experience that is complex, contingent and contextualised. Using interview, focus group and observation data conducted with 15 first-year undergraduate social science students at a UK research-intensive university, this paper explores how students negotiate the complex knowledge practices that constitute critical thinking, particularly the affects of being and becoming critical. The theoretical tools offered by Karen Barad and Sara Ahmed allow a conceptualisation of critical thinking as a complex phenomenon of socio-material and affective practices. This paper turns to Barad and Ahmed to explore the potential of their clashing theorisations for thinking through the affective territories of critical thinking. It will argue that acknowledging the way(s) critical thinking feels (as well as what it is and what it is for) opens up new imaginaries for feminist scholarship about criticality.