Recent developments in the micrometeorological theory needed to interpret flux measurements in complex terrain will be presented. The problems of measuring fluxes under stable conditions will be discussed, followed by presentation of preliminary results of flux measurements from the developing OzFlux network. Diverse ecosystems are being studied and for a variety of objectives: the Australian sites include the wet/dry tropics in the Northern Territory and N. Queensland, a tropical rain forest, sugar cane plantations and a cool temperate Eucalyptus forest. The New Zealand study is over agricultural land while the Vanuatu site is in a coconut plantation. Fire is a major ecological factor in savannas, and the effects of fires on heat, moisture and carbon dioxide fluxes to the atmosphere is the focus of the study by the Northern Territory group. Interannual variability in global CO2 concentrations are strongly affected by savanna fires. The dynamics of the productivity and water use of wet/dry savanna in a major river catchment in N. Queensland are being studied by CSIRO. These ecosystems are heavily grazed and research focuses on effects of current climate variability and future higher CO2 levels on water use efficiency of the ecosystem. James Cook University has mounted instruments on a large industrial crane located in tropical rainforest. A tropical cyclone severely damaged the forest soon after installation of the crane and the JCU group is now tracking the changes in microclimate and canopy productivity of the rainforest following the cyclone. The main objective of the sugar cane site in tropical Qld is to provide accurate estimates of crop evapotranspiration and to determine the CO2 balance of the Australian sugar industry. Productivity and water use of the tropical ecosystems are being contrasted with a 40 m tall Eucalyptus forest in SE New South Wales by CSIRO. The temperate forest is the most productive of all the FLUXNET sites, and this high productivity is a