Excitation/emission matrix (EEM), single-scan excitation and synchronous fluorescence spectra of a series of FA and HA from distinct environments are presented. The EEM plots show at least four spectral features whose corresponding Ex/ Em pairs relate to the α′, α, β and γ (or δ) fluorophores previously found in natural waters spectra. The α′ and α peaks, which identify typical humic-like components, are present in all samples, independently of the organic matter (OM) source. In FA, their Ex/ Em pairs are ∼260 nm/460 nm and ∼310 nm/440 nm, respectively. In HA their excitation and emission maxima are red-shifted, the corresponding Ex/ Em pairs being located at ∼265 nm/525 nm and ∼360 nm/520 nm, respectively. The appearance of β and γ (or δ) peaks is dependent both on the OM origin and on HS aging. The former ( Ex/ Em ∼ 320 nm/430 nm), that has been associated with the incidence of marine humic-like material, is present only in a few marine and estuarine HA. It emerges as a shoulder on the α peak and its detection is dependent on a balance between its magnitude and the magnitude and emission maxima location of the α peak. The γ (or δ) peak ( Ex/ Em ∼ 275 nm/315 nm in FA, and ∼275 nm/330 nm in HA), on the other hand, is better visualized in FA than in HA diagrams. It has typical protein-, mainly tryptophan-like, fluorescence properties and appears with varied significance in a few marine and estuarine samples being hardly detected in samples from exclusively terrestrial environments. It is also shown in this study that with selected λ ex, λ em and Δ λ values, regular emission, excitation and synchronous spectra can, together, provide a good picture of the OM sources and aging for extracted HS.