Models describing the moisture content of forest fuels are an integral component of most fire behaviour prediction systems. In this paper, models of all aspects of moisture change in fine, dead, surface litter are examined and reviewed. Included are models describing the changes in moisture content associated with isothermal vapour exchange by absorption processes, and the effects of precipitation and condensation of liquid water. Models for predicting fuel temperature and humidity, and equilibrium moisture content are also assessed. Critical reviews of the assumptions underlying each model are made, and points of comparison and contrast explored. Some recommendations for future research are suggested.