Volumetric mass transfer coefficient and gas holdup in bubble column was studied experimentally under pressurized condition with variation of liquid phase, diameter of single nozzle used as gas disperser. The pressure in the bubble column was in the range 0.1-1.1 MPa. Gas holdup and volumetric mass transfer coefficient increased with pressure. The effect of pressure on gas holdup and volumetric mass transfer coefficient appeared significantly in the case where the single nozzle with smaller diameter were used as gas disperser. Experimental equations for both gas holdup and volumetric mass transfer coefficients under small volume of gas chamber were presented incorporating the effect of pressure, diameter of single nozzle used as gas disperser and gas velocity.