Using electronic-reverse auction (e-reverse auction) offers many advantages to companies such as price reduction, decrease in cycle time, standardization, and transparency in purchasing process. Despite its great advantages, some users do not want to use e-reverse auction technology for the procurement of products or services. This study aims to understand factors affecting e-reverse auction usage in companies by integrating three important theories. Key constructs of technology acceptance model (TAM). theory of planned behavior (TPB), and innovation diffusion theory (IDT) are integrated to explain behavioral intention to use and actual use of e-reverse auction. Using LISREL 8.54, data collected from 156 employees working in the procurement department of companies in 40 different countries were used to test the proposed research model. Results indicated that, 76% of employees' intention to use e-reverse auction is explained by subjective norms, perceived behavioral control, and perceived usefulness. Among them, subjective norms have the strongest effect. Besides. actual use of e-reverse auction is directly predicted by behavioral intention to use. We conclude with managerial implications and recommendations for possible future research. (C) 2009 Elsevier Ltd. All rights reserved.