Radial bubble velocities, chord lengths, and local gas holdups were measured by a dual-tip conductivity probe in a slender particle-containing scrubbing-cooling chamber. The annulus region of the bubbling bed was divided into three regions according to the radial distributions of bubble velocity, bubble size, and local gas holdup. Bubble velocity distributions were obtained by the kernel density estimation, and the relationships between mean bubble velocity and diameter were discussed. The interfacial area was calculated by the size distribution of total bubbles in the bed which was transformed from that of total bubbles touching the probe by an analytical transformation method. Effects of superficial gas velocity, fiber volume fraction, and aspect ratio on the distributions of bubble velocity and interfacial area were discussed. The experimental interfacial area values were in good agreement with the calculated ones obtained by the modified Besagni and Inzoli correlation.