The use of e-procurement aids organisations in reducing business costs, broadening their market access and simplifying purchasing processes. However, in Jordan, only 27.6% of firms utilise e-procurement systems. Hence, the usage of e-procurement systems by Jordanian firms is still in its infancy. In this work, the technology, organisation and environment (TOE) factors affecting the use of e-procurement systems by large firms in Jordan were investigated. Previous studies have reported inconsistent findings with regard to the antecedent factors that may affect e-procurement usage. Therefore, this work aimed to determine the factors related to e-procurement usage and whether or not top management support moderates the relationship between TOE factors and e-procurement usage. Results revealed that all TOE factors used in this study influenced the e-procurement usage of the firms. Moreover, the moderating role of top management support was found to be positively related to relative advantages and organisational readiness and negatively related to complexity.