The mass transfer reaction kinetics of beta-isophorone (beta-IP) oxidation reaction by air was investigated in a lab-scale agitator bubbling reactor. This reaction can be regarded as instantaneous and there exists a critical concentration of beta-IP. When the catalyst concentration is kept unchanged, the reaction rate is only controlled by the gas film and the reaction kinetics is of zero order with respect to beta-IP when the beta-IP concentration lies over the critical concentration. The reaction rate is controlled by the dual film and the kinetics is of first order with respect to beta-IP when its concentration is below the critical concentration. Under the gas film-controlling condition, the effect of temperature, agitator speed, and aeration on the reaction rate is evaluated. A correlation equation of gas phase volumetric mass transfer coefficients combining superficial gas velocity and agitator speed is defined.