There is scarce research in the domain of sustainable marketing and renewable energy, despite the importance of this area. The consumers should adopt and increase the use of renewable energy (RE) because renewable energy sources contribute to reduce the dangerous gas emissions and resource depletion. Therefore, the understanding of what drives the consumer demand for RE is essential. Sustainable marketing has an important role in creating and promoting sustainable patterns and levels of consumption of the end users. In this study, considering the theory of reasoned action (TRA), the knowledge about renewable energy (RE_KNOW), the attitude toward RE (RE_ATT), the willingness to pay more for RE (RE_WPM) and the predisposition to ecological consumer behaviour (ECCB) were analysed as determinants of the intention to use RE (RE_INT). Moreover, the effects of RE_KNOW on RE_ATT and on ECCB and the effects of RE_ATT on ECCB and on RE_WPM were also assessed. Based on an online survey, the reliability, and convergent and discriminant validity of the constructs were assessed presenting good values. Structural equation modeling (SEM) was used to test the proposed relations. The results confirm all the determinants of RE_INT except the RE_WPM. The ECCB is the stronger determinant of the RE_INT, followed by the RE_ATT. The beliefs – attitude – intention link was found which supports the TRA. The effect of RE_KNOW is stronger on ECCB than on RE_ATT, and the effect of RE_ATT is stronger on ECCB than on RE_WPM. Furthermore, the moderator effects of sex and age were evaluated through multi-group analysis. For women and men, the proposed relations do not have significant differences. However, for the younger group, RE_ATT is the only significant determinant of RE_INT whereas, for the older one, ECCB and RE_WPM are the significant ones. For younger individuals, RE_KNOW has a direct, positive effect on RE_ATT which in turn has a direct, positive and strong effect on RE_INT, in accordance with the theory of reasoned action; RE_ATT has a direct, positive and stronger effect on ECCB than RE KNOW has. For older individuals, the relation RE_KNOW– RE_ATT – RE_INT is not significant. This research offers insights that help the electricity companies to develop sustainable marketing strategies in order to increase the use of RE. The results of this study indicate that the theory of reasoned action broadly support the attitude-behavior link for consumer RE use. However, for specific groups, the older one, this is not the case. To capture younger consumers it is important that companies develop marketing strategies to increase RE_KNOW and consequently to strengthen RE_ATT to obtain strong RE_INT and RE use. However, to conquer older consumers the effort should be putted more on the reinforcement of ECCB and on the RE_WPM. Therefore, the marketers need to develop different strategies for different target groups to promote the electricity products. Campaigns about renewable energies, their advantages and impact on the environment should be targeted to younger consumers in order to increase the knowledge and attitude toward RE However, to attain more willingness to pay a price premium for green electricity by the older consumers, the companies should document and communicate well the environmental benefits of their green offers. Moreover, for this older group, the promotion of other consumer sustainable behaviors will be desirable since they will have a positive impact on the intention to use RE.