The characterization of four galactomannans from the seeds of Mimosaceae spp., from natural Southern Brazilian sources having similar chemical structures with Man:Gal similar to 1, was performed. (CNMR)-C-13 spectra gave clear information on the chemical structure of these highly branched galactomannans. Their physico-chemical macromolecular characteristics were determined from SEC experiments, leading to the determination of parameters relating R-G and [eta] with M-w. Applying a model of worm-like chain, a persistence length of L-p similar to 100 Angstrom was determined. The specific viscosity at zero shear rate was investigated, and demonstrated that a unique curve relates eta(sp) With the overlap parameter C[eta]; in the range of higher values of C[eta], the slope was n = 6.2; the critical concentration c*[eta] = 1.9. Considering the structure and rheological properties, galactomannan from Mimosa flocculosa and Mimosa bimucronata might be potentially applied as thickeners in food and cosmetic products, as well as galactomannan from Mimosa scabrella Benthan, previously analysed.