Paper presented at the the 13th International Conference on Knowledge Management and Knowledge Technologies: “Open Government Data (OGD) stands for a relatively young trend to make data that is collected and maintained by state authorities available for the public. Although various Austrian OGD initiatives have been started in the last few years, less is known about the validity and the usefulness of the data offered. Based on the data-set on Vienna’s stock of trees, we address two questions in this paper. First of all, we examine the quality of the data by validating it according to knowledge from a related discipline. It shows that the data-set we used correlates with findings from meteorology. Then, we explore the usefulness and exploitability of OGD by describing a concrete scenario in which this data-set can be supportive for citizens in their everyday life and by discussing further application areas in which OGD can be beneficial for different stakeholders and even commercially used.”