The influence of magnetic field on local gas holdup, epsilon(g) and average gas holdup <(epsilon)over bar>(g) has been studied in a three-phase (gas-liquid-solid) magneto-fluidized bed using electroresistivity probe technique and quick closing valve technique, respectively. The local gas holdup shows a linear variation with dimensionless radius at low gas velocities and parabolic variation at high gas velocities with maximum at the centre and minimum at the wall. Higher values of epsilon(g) are obtained in presence of field than in absence of magnetic field. Average gas holdup <(epsilon)over bar>(g) decreases with field intensity upto H = 52.8 Oe and shows an increase beyond this field intensity. The <(epsilon)over bar>(g) values obtained by first fluidizing the bed and then magnetizing it have been found to bt:higher than those obtained by reversing this sequence.