This paper presents an application of "chaos" or "deterministic chaos" analysis to the performance of a gas-solid fluidized bed. From the point of view of the still developing field of chaos the significance of this analysis is the constancy of the correlation dimension and the Lyapunov exponent over a range of operating conditions. From the point of view of fluidized bed theory these quantitative numbers provide a method of characterizing performance. In addition, in the latter case, the presence of the chaotic attractor indicates several general properties of this dynamical system.