The biodiesel synthesis intensification can be performed using microdevices. The present research investigated numerical and experimentally the transesterification of sunflower oil with ethanol and sodium hydroxide catalyst in microchannel reactors with static elements. In the numerical study, two micro mixer designs (Length = 35 mm; Width = 1500 mu m, Height = 200 mu m) were evaluated: T-micromixer (micromixer without static elements) and MSE (micromixer with static elements). The mixing of fluids was analyzed for a range of Reynolds number of 0.1-100. The oil conversion was investigated for a range of operating conditions: temperature (25-75 degrees C), ethanol/oil molar ratio (6-12) and catalyst concentration (0.75-1.25%). Similar conditions were experimentally tested in microchannels with static elements (Length = 411 mm) made of polydimethylsiloxane (PDMS). The MSE showed superior performance of mixing index and oil conversion. The highest mixing was noticed for a Reynolds number of 100. The optimum oil conversion (91.53%) was observed numerically at conditions of 75 degrees C, ethanol/oil molar ratio of 9 and catalyst concentration of 1%. The MSE showed experimentally the highest ethyl esters percentage (99.53%) at 50 degrees C, ethanol/oil molar ratio of 9 and catalyst concentration of 1%, for a residence time of approximately 12 s. The use of static elements in micromixer enhanced the biodiesel synthesis. (C) 2016 Elsevier Ltd. All rights reserved.