Background and aims: Behavioural and pharmacological support for smoking cessation improves the chances of success and represents a highly cost-effective way of preventing chronic disease and premature death. There are a large number of clinical stop-smoking services around the world. These could be connected into a global network to provide data to assess what treatment components are most effective, for what populations, in what settings. This requires data to be collected according to a minimum standard set of data items. This paper sets out a proposal for this global minimum data set. Methods: We reviewed sets of data items used in clinical services that have already benefited from standardised approaches to using data. We identified client and treatment data items that may directly or indirectly influence outcome, and outcome variables that were practicable to obtain in clinical practice. We then consulted service providers in countries that may have an interest in taking part in a global network of smoking cessation services, and revised the sets of data items according to their feedback. Results: Three sets of data items are proposed. The first is a set of features characterising treatments offered by a service. The second is a core set of data items describing clients characteristics, engagement with the service, and outcomes. The third is an extended set of client data items to be captured in addition to the core data items wherever resources permit. Conclusions: We propose minimum standards for capturing data from clinical smoking cessation services globally. This could provide a basis for meaningful evaluations of different smoking cessation treatments in different populations in a variety of settings across many countries.