Environmental education and computers? That was traditionally seen as an antagonism. But environmental educators who compete for attention and face new challenges in an age of mobile devices, have begun to explore the opportunities that mobile computers may offer in supporting environmental learning experiences. This study investigates the impact of a mobile guide system on different parameters of environmental literacy in comparison to traditional instruments of environmental education (i.e. brochure, human guide). In a field experiment at a floodplain conservation site, 185 school children and 76 adults participated in a guided tour using different media. Despite the novelty of mobile devices and usability issues associated with the prototype mobile nature guide, participants using the computer-assisted medium achieved similar results concerning environmental literacy components. The computer as mobile guide can lead to an increase in environmental knowledge and in case of the children it can increase their motivation to engage in environmental education activities. (Contains 4 tables and 9 figures.)