The effect of doping of strontium/silica (Sr40/ Si-A_octa) catalyst by barium on its kinetics of methanol transesterification of sunflower oil (MTSFO) to biodiesel was investigated. The experimental data of MTSFO over Sr40/Si-A_octa appear to be good fit into pseudo first order kinetic mechanism. However, the zero-order rate equation is the best fit model for MTSFO over BaSr40/Si-A_octa, compared with the pseudo-first order and second-order rate kinetic models. On the other hand, the intraparticle diffusion kinetics model may also play an important role in the MTSFO over BaSr40/Si-A_octa. In addition, a significant change was observed in Arrhenius activation energy of MTSFO over Sr40/Si-A_octa when it dopped by Ba. Where, Arrhenius activation energy values were found to be 16.6 and 49.6 kJ mol^-1 for Sr40/Si-A_octa and BaSr40/Si-A_octa , respectively. These results can be suggested that addition of Ba toSr40/Si-A_octa can enhance its catalytic performance in selective MTSFO.