An osmotic device (10) for the controlled systemic delivery of nicotine through an oral mucosal membrane of a human patient is disclosed. The device (10) has a size and shape adapting it to be comfortably retained in the mouth for extended periods of time. The device (10) comprises a semipermeable wall (12) surrounding a compartment (13) containing a nicotine salt (14) and optionally an alkaline salt which is capable of reacting with the nicotine salt in the presence of water to form nicotine base. Nicotine base is delivered from the compartment (13) through a passageway (17) in the wall (12). The nicotine salt exhibits good stability and shelf life while the nicotine base exhibits excellent absorption through oral mucosal membranes.