The objective of this study was the fully characterization of the pruning wastes from macrophyte Cyperus giganteus from tertiary sewage treatment of Wastewater Treatment Plant, Ponte dos Leites, located in Araruama, RJ, Brazil. Such analyses aimed at the systematic evaluation of the feasibility of using the pruning material as an energy input. To reach the objectives, the macrophytes were submitted to experimental analyses of their physical properties (Specific density: 0.44-0.77 g.cm -3 , Bulk density: 0.08-0.09 g.cm -3 , among others characteristics), chemical and immediate analysis, and thermal analysis. The results of thermal behavior characterized the biomass as a viable energy source (High Heat Value 14-16 MJ.kg -1 ). Focused in its pre-treatment for energy use, C. giganteus different samples fractions analyses confirmed that the molecular structures of the macrophyte (Lignin: 17.32-26.83 wt%, Cellulose: 27.84-32.65 wt%, Hemicellulose: 30.09-31.46 wt%; depending on the part of the plant) affect the mechanisms of thermal decomposition. Pyrolysis processing yields vary from 83.43 to 75.91%. This shows the effectiveness of the technique adopted in the transformation of the analyzed vegetal residues into raw materials for energy generation, evidencing the energy potential of the biomass and, confirming the use of these as raw materials in thermo-conversion processes.