Todays’ geoportals still show various usability issues, which could result in inefficient usage or usage mistakes. This poster submission describes how to use usability tests to discover usability problems in geoportals and how to develop guidelines, so-called usability patterns, which offer best practice solutions to improve the usability of geoportals. We performed a usability test and used the results to develop two usability patterns for geoportals focussing on map usage as an initial subset of usability patterns for GI Web applications.