Abstract:Transportation is a major contributor of carbon dioxide and other greenhouse gas emissions from human activity. It accounts for approximately 14% of total anthropogenic emissions globally and about 27% in the United States. Growing concern regarding the impacts of climate change and greenhouse gas emissions, along with petroleum dependence and energy security, has led to innovations in automotive and fuel technology. However, the behavioral response to the newest transportation technologies, such as hydrogen fuel-cell vehicles (FCVs) and fueling infrastructure, is not well understood. The results of an exploratory hydrogen FCV fleet study, which focused on fleet drivers' attitudes and perceptions over a 7-month period in 2006, are examined. The study employed a longitudinal survey design, with three phases and one focus group. There were limitations to the exploratory data set generated from this study (e.g., small sample size, self-selection bias, and generalizability). However, the results provided insights into participants' responses to the FCV and hydrogen fueling infrastructure over time and could help to inform further inquiry. Higher levels of hydrogen exposure were correlated with increased comfort with hydrogen, especially among those who were less experienced. Early adopters of the technology generally felt safer driving the FCV than later adopters. Respondents mostly felt safe refueling the FCV. As experience with the FCV increased, participants felt increasingly safe with the vehicles. The driving range was considered a limitation. Furthermore, over the course of the study, participant perception of vehicle range increased because of learning.