Insectivorous or micro-bats are a notoriously difficult group of mammals to survey because they are small, nocturnal, fly and roost in hard to reach places during the day. However, micro-bats should not be neglected from biodiversity assessments because they play pivotal roles in pest regulation and as biological indicators. We used acoustic receivers (n = 20 trap nights) to sample micro-bat species richness at three sites within the Mapungubwe National Park, South Africa during the austral winter and summer of 2013. Twenty micro-bat species from six families were recorded, with the plain-faced/clutter-edge foraging bats (Miniopteridae and Vespertilionidae) and free-tailed (Molossidae) or open-air foraging bats dominating. Bat activity was significantly higher in summer compared to winter and this is likely linked to higher prey availability and reduced thermoregulatory costs at this time. Our results represent the first comprehensive assessment of micro-bat species richness in the Mapungubwe National Park and our data compare favourably with historical records for the region. In addition, we provide evidence for the presence of at least one undescribed species. We advocate the use of acoustic receivers for future micro-bat surveys as long as comprehensive reference call library data are available.