The dematerialisation of public procurement (hereinafter e-procurement) is one of the most innovative public management initiatives in Europe today. However, according to European statistics, the acceptance of this new public procurement technology by private companies remains very limited. And despite the existence of an abundant literature dealing with the acceptance of technology, in the field of e-commerce for example, very few studies have addressed the field of e-procurement. The aim of this article is to analyse the latter by making a distinction between the acceptance determinants of e-procurement by SMEs, on the one hand, and by large companies, on the other. Based on several theories on the acceptance of innovation in general, and on the acceptance of technology in particular - the Technology Acceptance Model (TAM); the Diffusion of Innovation Theory (DIT); and the model of Iacovou et al. - we developed a model and tested it on a sample of firms. The results of the survey, covering 695 SMEs and 126 large companies in Belgium, have enabled us to identify four main factors that can account for about 33.4% of the total variability in the acceptance of e-procurement by SMEs. In addition, we have identified two factors that could account for around 28.5% of the total variability of e-procurement acceptance by large firms.