Characteristics of pressure fluctuations and liquid dispersion in the radial direction were investigated in the riser of a liquid-solid circulating fluidized bed whose diameter was 0.102 m and 3.5 m in height. The concept of chaos theory was employed to analyze the pressure fluctuations obtained in the riser. Effects of liquid velocity, particle size, and solid circul ation rate on the liquid radial dispersion coefficient and phase space portraits and correlation dimension of pressure fluctuations were determined. It was found that the radial dispersion coefficient of liquid phase increased with increasing particle size or solid circulation rate, but decreased with increasing liquid velocity. The attractor in the phase space portraits became more scattere d and complicated with increasing particle size or solid circulation rate, but it became somewhat less scattered with increasing liquid velocity. The correlation dimension of pressure fluctuations increased with increasing particle size or solid circulation rate, but it did not change considerably with increasing liquid velocity. The results of this study enable us to predict the characteristics of liquid radial dispersion by means of the pressure fluctuations for the practical applications.