This manuscript considers the implications of prior attitudes for public-facing communication campaigns relating to hydrogen technologies in Europe. Findings from a survey of publics in seven EU countries indicate low attitude strength and low stability of attitudes towards hydrogen fuel cells for stationary and mobile applications, as well as country differences. While prior attitudes are known to be influential in technology acceptance, they appear to be less so at the early stage of technology diffusion, when public knowledge and awareness are relatively low. This in turn implies that while psychological theories are proving useful in consumer-citizen aspects of socio-technical transitions research in particular, their context-specific application and further empirical testing are required. The findings imply that information campaigns would be a valuable tool at this early stage of hydrogen technologies, being likely to increase awareness for those with low or no knowledge and to positively influence attitudes towards the technology. Assuming higher diffusion of the technologies in future, however, communication strategies would need to be adapted: stronger commitment towards particular attitudes may lead to ‘biased’ information processing and evaluation. Regular monitoring on a country-specific level in this regard is thus recommended, reflecting country differences in the degree of diffusion of hydrogen technologies.