Background and Aims Most e‐cigarette users who also smoke combustible cigarettes (dual users) begin vaping to quit smoking, yet only a subset succeeds. We hypothesized that reinforcing characteristics of e‐cigarettes (vaping reinforcement) would positively predict smoking cessation propensity (SCP) among dual users.

Design Secondary analysis of cross‐sectional baseline data from dual users in an ongoing smoking cessation trial. Exploratory and confirmatory factor analysis (EFA and CFA) created latent variables for vaping reinforcement and SCP. A structural equation modeling (SEM) approach was used to test the hypothesis.

Setting United States.

Participants A national sample of dual users of combustible and electronic cigarettes who smoke and vape at least once per week (n = 2896) were enrolled (63% male; mean age = 29.9 years) into a randomized controlled trial in which they would receive either smoking cessation materials or no smoking cessation materials.

Measurements Vaping reinforcement was indexed by vaping frequency (days/week vaping, times/day vaping, puffs/e‐cigarette use), e‐cigarette characteristics [numbers of modifications and tobacco or non‐tobacco flavors, nicotine content (mg) and positive e‐cigarette expectancies]. SCP was measured by items of confidence, commitment to being smoke‐free, cessation motivation (contemplation ladder), change in cigarettes per day since beginning e‐cigarette use and negative smoking expectancies.

Findings Four factors emerged from the EFA: vaping propensity (vaping frequency, positive expectancies), vaping enthusiasm (e‐cigarette modifications, using non‐tobacco flavors, puffs per use), nicotine/tobacco flavor (nicotine strength, tobacco flavors) and SCP (negative expectancies about smoking, motivation to quit smoking, reduction in smoking). A CFA upheld the exploratory factor structure [root mean square error of approximation (RMSEA) = 0.046, CFI = 0.91]. An SEM with the three vaping latent variables directly predicting SCP had good model fit (RMSEA = 0.030, CFI = 0.97) with a positive relationship of vaping propensity (0.509, P < 0.001), and small negative relationships of vaping enthusiasm (−0.158, P = 0.014) and nicotine/tobacco flavor (−0.230, P < 0.001).