This paper elaborates a process followed to characterise manifestations of cognitive regulation during the collaborative planning of chemistry practical investigations. Metacognitive activity was defined as the demonstration of planning, monitoring, control and evaluation of cognitive activities by students while carrying out the chemistry task. Inherent in collaborative learning is the social aspect of metacognition, which in this study was evidenced in social cognitive regulation (notably of intra- and interpersonal metacognitive regulations) as groups of students went about planning their practical investigations. Discussions of two of the learning groups (n = 4; n = 3) as they planned the extended practical investigation were recorded, transcribed and analysed for indicators of any inherent metacognitive activity. The process of characterising the manifestations of metacognition resulted in the development of a coding system which specifies not only the regulatory strategies at play but the type of regulation ("self" or "other"), the area of regulation ("cognition," "task performance" or "behaviour") as well as the depth of regulatory contributions ("high" or "low"). The fine-grained coding system allowed for a finer theoretical elucidation of the social nature of metacognition. The implications of this study for metacognition and chemistry education research are highlighted.