Time-resolved fluorescence measurements of aquatic natural organic matter (NOM) derived from different origins were performed using the time-correlated single-photon counting technique. The obtained experimental data were analyzed with nonlinear least-squares (NLLS) algorithms. The results of a global analysis with three exponential decay terms were compared with the results obtained in a distribution analysis (exponential series method; ESM). Fulvic acid fractions from a bog lake water, from a brown coal production effluent, and from a soil seepage water as well as NOM from a municipal waste water were investigated. The influence of the emission wavelength on the NOM fluorescence decay was monitored. Furthermore, the influence of fractionation using size exclusion chromatography, of ozonation, and of metal ion complexation on the fluorescence decay of the NOM samples was investigated.