The effects of the geometric properties of the perforated plate used as a gas distributor on average gas holdup,phi, were cyperimcntally investigated in a bubble column. The geometric properties of hole diameter, d, the number of holes, n, and the hole pitch, p, were varied as follows: d=0.5, 1.0 and 2.0mm; n=22, 88, 352, 864 and 1766; and p = 0.7, 1.0, 1.6, 2.0, 3.0 and 6.2 cm. The hole arrangement on the perforated plate was a regular triangle. The clear liquid height, Z(0), was 0.64 and 1.92 m. For the entire range of superficial gas velocity, u(G0), covered in this Study, the highest values of 0 were obtained with the perforated plates having d 0.5 mm, n 864, p = 1.0 cm and d 0.5 mm, n= 1766, p-0.7 cm at both values of Z(0). The value of phi obtained with the perforated plate of d=0.5 mm, n=88, p = 0.7 cut was the smallest at both values of Z(0). An empirical correlation predicting the bubble free rising velocity was obtained by use of the dimensional parameter np/dD(T)(2).