As part of large scale survey research, this study examines the notion of assimilation of public procurement innovation (e-procurement) and proposes a conceptual model that may facilitate a greater understanding of how organizations can effectively manage the process of e-procurement assimilation in the light of transaction cost theory. A pilot study with over 40 procurement professionals in the Australian public sector was conducted to refine the survey instrument, which was initially developed through an extensive literature review. A survey endorsed by various Australian public sector agencies revealed significant relationships between the transactional cost antecedents (independent variables) and the e-procurement assimilation. Structural Equation Modeling results suggest that while no support was found for the negative relationship between Perceived Increase in Transaction Costs and the e-procurement assimilation, only partial support was found for the assocation beween transaction uncertainties and e-procurement assimilation. The study also found that there was a positive association between transaction frequency and the dependent variable. The understanding of the key antecedents of e-procurement assimilation in the light of transaction cost theory will help put practioners in a better position to formulate and implement appropriate strategies to cope with the challenges of their e-procurement implementations