Although there is only negligible rainfall, frequent nocturnal fog, dew and high air humidity support a luxurious lichen vegetation in the coastal zone of the central Namib Desert (Namibia). In earlier publications, we have studied ecophysiological performance of a series of epilithic and terrestrial lichens. Here, we have extended this work to three epiphytic species (Heterodermia namaquana, Ramalina lacera, and Xanthoria turbinata) that inhabit the sparse perennial shrubs growing in this area. Our intention, monitoring lichen CO2 exchange, their water relations and microclimate conditions, was to determine the functional mechanisms that allow these epiphytes to exist under the special conditions of a fog desert. Measurements were conducted mainly during the spring season. Keywords: dew, photosynthesis, production, Heterodermia namaquana, Ramalina lacera, Xanthoria turbinata.