This work contains a description for the determination of the liquid phase molar transfer coefficient (K(X)a) by a method which is different from that by Onda correlation. The method is different because K(X)a is for the transfer of the tars which change their phase and size as the temperature and pressure change. In the method, the solubility of the tars in biodiesel was predicted and ultimately the equilibrium coefficient was calculated. The equilibrium coefficient and measured tars compositions in liquid and gas phases at steady state were used to determine K(X)a. In this way, the determination of K(X)a for the wet scrubbing of tars into biodiesel was achieved semiempirically. The predicted equilibrium coefficient of the 0.3818 mole ratio at liquid phase temperature of 300 K and atmospheric pressure was used in the calculation. Under these conditions, K(X)a depended on the liquid to gas flow rate ratio, the inlet and outlet liquid phase compositions, and the exit gas composition. As a result, the measured values of these parameters together with the predicted equilibrium coefficient were fitted into a semiempirical correlation defined as K(X)a = 0.0143L(0.7704)G(0.0282). This fitting is reasonably satisfactory as it satisfies the conditions cited in the literature and can be effectively applied at liquid to gas flow rate ratios of 36 and 38.