Purpose – This paper presents an extended technology acceptance model (TAM) with concepts from the innovation diffusion theory (IDT) and customers’ perceived risk, aiming to examine the factors affecting Greek customers’ intentions to adopt internet banking services. Furthermore, several individual differences are examined, with respect to their impact on the formation of customers’ attitude about the pros and cons of the new technology. Design/methodology/approach – Based on an empirical study including off-line banking customers that are familiar with the internet, the authors validate a causal model linking the constructs of the proposed service’s compatibility, perceived ease of use, perceived usefulness, perceived security and privacy risk, customers’ demographics and IT competences, with customers’ intentions to adopt internet banking services in the future. Partial least squares procedure was used to analyze 212 cases collected from residential customers via personal interviews using a properly designed questionnaire. Findings – The results indicated that service compatibility is the key factor, which mostly shapes customers’ behavioural intentions toward internet banking adoption, followed by TAM constructs and perceived risk elements. Moreover, TAM and perceived security and privacy risk constructs partially mediate the relationships between compatibility and customers’ behavioural intentions, while perceived usefulness partially mediates the relationship between perceived ease of use and customers’ intentions. Finally, in terms of the impact of individual differences on customers’ beliefs about internet banking compatibility, value and risk elements, younger, mostly male customers, with adequate previous IT experience who find themselves to be compatible with the new service, are a more promising target group to use internet banking, as an alternative channel to perform their financial transactions in the future. Originality/value – This study explores the influence of an extended TAM model factors on internet banking adaptation behaviour of Greek customers. The proposed model has never been used in the internet banking context and could be utilised to provide a solid theoretical foundation of the internet banking acceptance case.