In recent years, Open Data has gained considerable attention: a steady growth in the number of openly published datasets – mainly by governments and public administrations - can be observed as the demand for Open Data rises. However, many potential providers are still hesitant to open their datasets and at the same time users often face difficulties when attempting to use this data in practice. This indicates that there are still various barriers present both regarding usage and publishing of Open Data, but studies that systematically collect and assess these barriers regarding their impact are rare. Based on this observation we survey prior literature on barriers, and have developed a questionnaire aimed at both assessing the users and publishers views on obstacles regarding Open Data adoption. Using a sample of over 100 participants from Austria who completed our online survey, we draw conclusions about the relative importance of the barriers reported in the literature. The empirical findings presented in this study shall serve as a solid foundation for future research on the mitigation of Open Data barriers.