Purpose – This paper seeks to contribute to a more effective co-ordination of humanitarian operations by military and civilian organizations involved in a peace support mission in response to a complex emergency. Design/methodology/approach – The information processing view, in particular Galbraith's typology of generic mechanisms for achieving co-ordination, is taken as the theoretical framework. This framework is subsequently applied to the co-ordination of humanitarian operations by military and civilian organizations. Empirical data are derived from a set of expert interviews with both military and civilian respondents in The Netherlands and a four week visit to Kabul and Baghlan, a province in northern Afghanistan. During this visit 40 military respondents have been interviewed and over 60 meetings have been held with local authorities, humanitarian organizations, small entrepreneurs, refugees and local villagers. Finally, conclusions are drawn and recommendations are provided with regard to a more effective co-ordination of humanitarian operations in a peace support mission. Findings – The article's main finding is that “self-contained tasks” in combination with lateral relations are the dominant co-ordination mechanisms. “Slack resources”, though observed in practice, is not considered a viable co-ordination mechanism since this implies an excess, and thus waste, of scarce resources. “Information systems” are, unfortunately, not well-developed leading to mismatches between policy and practice. Keeping “self-contained tasks” as the major co-ordination mechanism, the main recommendation is to develop and implement innovative “information systems”, that can also be used to support “lateral relations”, in particular those between military and civil actors. Originality/value – The paper applies the information processing perspective to a unique and important subject, namely co-ordination between military and humanitarian organizations in peace support missions.