Automation technology has received great attention recently and been expected to play an important role in future transport systems. Understanding determinants of travellers' intention to use the bus and recommend the service to others is critical to promote such new travel modes. Although previous studies have focused on plausible scenarios based on hypothetical behavioural reactions, predicted adoption intention and recommendation behaviour may not be consistent with those exhibited when the users are exposed to the real automated bus service. Using a panel survey conducted in Stockholm, where an automated bus services is currently operating in the mixed traffic environment on the public road, this study addresses this research gap by investigating public acceptance and usage of these automated buses. Applying a behavioural model, this study explores key influencing factors of automated bus use and word of mouth intention. The results indicate that users' needs and travel demands have a strong power to influence people's intentions to use such a new public travel mode and recommend the service to others. Furthermore, individuals' behaviour intention is found to have no significant effect on actual behaviour in this study, which suggests a gap between intention and action.