In spite of the frequent use of fluidized beds in coal and biomass combustion and gasification, few studies have experimentally characterized the hydrodynamic processes associated to fluidized beds. The non­linear character of the interaction of transport phenomena present in fluidized beds and the high number particle suggest that chaos theory can be a tool to analyze the hydrodynamics of fluidized beds. In this research we carried out experiments in an 8­cm­inner­diameter, 1.20­m height fluidized bed operated at 298 K and 86 kPa. Pressure vs. time data were recorded with a 30­ms dead time pressure transducer that was fast enough to measure the dynamic pressure fluctuations in the bed. P vs. t data were used to determine average ( x ), standard deviation (s ), skewness (S), flatness (F), auto­correlation function (Cxx) and the power spectral density function (PSD) by the mean Welch method. These variables allowed characterization of the gas­solid fluidized bed hydrodynamic according to chaos theory.