Politicians have high expectations for commercial open data use. Yet, companies appear to challenge the assumption that open data can be used to create competitive advantage, since any company can access open data and since open data use requires scarce resources. In this paper we examine commercial open data use for creating competitive advantage from the perspective of Resource Based Theory (RBT) and Resource Dependency Theory (RDT). Based on insights from a scenario, interviews and a survey and from RBT and RDT as a reference theory, we derive seven propositions. Our study suggests that the generation of competitive advantage with open data requires a company to have in-house capabilities and resources for open data use. The actual creation of competitive advantage might not be simple. The propositions also draw attention to the accomplishment of unique benefits for a company through the combination of internal and external resources. Recommendations for further research include testing the propositions.