This study investigated the use of ultraviolet (UV) and fluorescence spectroscopy to monitor the changes in biodegradability of dissolved organic matter (DOM) in landfill leachates. Experiments to investigate aerobic biodegradation of leachate DOM were carried out using untreated and treated leachate samples collected from two UK municipal solid waste landfills, L1 and L2. Leachate samples collected at different stages of the aerobic treatment processes were characterized by conventional methods (chemical oxygen demand (COD) and dissolved organic carbon content (DOC)) and also by UV spectroscopy and fluorescence excitation-emission matrix. The laboratory-scale aerobic treatment system achieved reductions in COD and DOC in all of the leachates. Results obtained from UV spectrophotometry indicated that the aromatic character of the leachate decreased during aerobic biodegradation. Additionally, the fluorescence intensity of the leachates decreased to various extents, suggesting degradation of humic, fulvic or protein-like structures during biodegradation. Initial results showed strong relations between fluorescent DOC and fluorescent COD and suggest that the strength of these correlations could be a useful tool in distinguishing sources and biodegradability of DOC cheaply and quickly, although further research using different types of leachates is required.