Microreactor technology offers better production profiles through effective heat transmission and mixing capabilities. In the present work, the potential of a microreactor was assessed for the synthesis of biodiesel from sunflower using a helical coil microreactor employing KOH as a catalyst for the transesterification reaction. The biodiesel synthesis was accomplished by a single-step transesterification reaction, and response surface methodology was used to optimize the process parameters. Using Box-Behnken design, the influence of various process parameters including the mole ratio of reactant (methanol:oil), residence time and catalyst loading were studied at 60 °C. A maximum yield of 93.27% was obtained at a 7:1 methanol to oil ratio with 1.12 wt% catalyst concentration and 1.4 min residence time. This work shows that the combination of helical continuous flow and transesterification offers researchers a special process-intensified procedure for the synthesis of biodiesel.