Voidage distribution along radial and axial directions in a cold flow semicircular fluidized bed 500 mm in diameter and 8000 mm in height was measured with a PC-4 optic fiber probe. The radial voidage profile is divided into jet and emulsion phase regions. The radial voidage profile in the jet region has an elliptic contour, but the voidage in the emulsion phase region is found to be equal to that under minimum fluidizating conditions. An empirical correlation for predicting the jet region voidage is proposed. The time series of pressure fluctuation are analyzed by deterministic chaos theory and power spectrum density function, and effects of jet gas velocity and static bed height on the correlation dimension and on major frequency are investigated. It is found that the major frequency (jet collapse frequency) increases with jet gas velocity. The results show that the correlation dimension increases with jet gas velocity. For a given jet gas velocity, the higher the static bed height, the greater the correlation dimension.