The presentation of information and interactivity on mobile devices has been a challenge for both information science and computing. In this environment, usability gains prominence and becomes central, be it commercial or public. In the public domain, transparency portals, also accessed from mobile devices, have interface peculiarities that may inhibit or enhance the use of apps created for this purpose. In this context, the present article analyzes the possible causes of the low use, in comparison to the accesses by computer or notebook, of the app Transparencia Movel-SC for mobile devices. The objective of the study was to identify possible difficulties that limit mobile users to access the system. While access to commercial websites through mobile devices exceeds 30%, access to the Transparencia Movel-SC app still remains below 1%. For this, usability tests were performed. Based on the results obtained, it is considered that the present research revealed the most critical difficulties that mobile users face during the use of the app Transparencia Movel-SC. It is believed that the difficulties encountered in this research can be used in the improvement of similar apps, which could generate its greater use by the citizens.