There has been much prior work into online service delivery in private firms, but little such work for governments. In particular, there has been little work into the value of online government self-service sites and how such value should be measured. This study seeks to identify and empirically test the potential value of webbased online Intelligent Support Systems (ISS) tools on government web sites. In the absence of prior practical work, this study uses a novel theory development process to develop a research model borne from literature theory, interview analysis and practitioner insight. The study finds that providing online ISS to citizens on government portal creates an empowerment effect and improves public perception of the government. Six constructs affecting effectiveness and impact are revealed, being decision making satisfaction, decision making transparency, perceived decision quality, government’s service provider image, perceived power relationship and user’s sense of control.