Ecosystem metabolism is an integrative measure of the processes controlling nutrient cycling andorganic matter dynamics in streams. Dissolved organic matter (DOM) is a supply of organic carbon and nitrogen for the aquatic food webs, and therefore has a direct and indirect impact on biogeochemical processes in aquatic ecosystems. The extent to which these organic forms of nitrogen and carbon are metabolized in freshwaters depends on the biogeochemical composition of DOM. Despite its recognized importance in freshwater system, characterization of DOM quality has been a focus on marine ecosystem rather than in river waters. Also, the source and importance of different organic matter quality in the stream channel can be altered by the land use in a streams's catchment. The aim of this study is to assess the link between the organic matter quality and ecosystem metabolism in the upstream of the Mara River with different land use/land cover.