Despite the rapid proliferation of open data platforms, the accessibility and ease of use of data portals is low. This factor prevents citizens and civil society organizations from exploiting open data for their goals. The poor usability of current generation of open data platforms could be attributed to the fact that these platforms were not designed for non-technical users. They are typically software products developed “by programmers for programmers or technical users”. Consequently, while reports about innovative use of open data by software developers and start-ups are common, there are very few reports about successful public use of open data to tackle concrete societal challenges. This paper provides the results and lessons learnt from the usability evaluation of the second alpha release of a next generation open data platform designed explicitly to support non-technical users. A scenario involving a transportation challenge in Dublin City was employed as the context for the evaluation of the platform. Findings provide some empirical basis for identifying important user interface design considerations, patterns for highly usable open data platforms and considerations for open data policy.