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INTRODUCTION: Reliable detection of cigarette smoking is necessary for just-in-time adaptive smoking cessation support. Smoking detection typically relies on intervention recipients to self-report smoking behaviours and their antecedents, which is burdensome and subject to reporting biases, or on specialised sensors and wearables to detect smoking gestures, which may not be feasible for real-world implementation. Here, we describe an observational laboratory-based study protocol designed to identify signature biomarkers and hand-mouth gestures associated with presmoking, smoking and postsmoking using off-the-shelf wearable devices.METHODS AND ANALYSIS: 30 non-treatment seeking individuals who use combustible tobacco products will participate in the study. Participants will be monitored for 1 hour in a smoking chamber, during which time they will wear a Garmin device that will collect hand/arm movement, heart rate, heart rate variability, blood oxygenation and respiratory rate. First, participants will be in a nicotine-deprived state based on 12-hour abstinence validated by exhaled carbon monoxide readings (~20 min). Then, participants will be allowed to smoke cigarettes of their choice (~10-15 min). Finally, participants will be in a nicotine-satiated state (~25 min). Participants will be video recorded to allow us to label the data corresponding to the smoking stage and behaviour. We will conduct time-series analysis and analysis of variance to quantify changes in biomarkers between smoking stages.ETHICS AND DISSEMINATION: The Institutional Review Board of the University of Kansas Medical Centre approved the study on 21/3/2025 (STUDY00161139). Participants will provide informed consent to participate in the study. Data collection is expected to begin in September 2025 and results will be submitted for publication in 2026.TRIAL REGISTRATION NUMBER: NCT07067151.