The paper reports an experimental investigation on the effect of geometrical design of double jet impingement microchannels on mixing efficiency. Three arrangements of microchannel reactors (MCRs) were designed with 800 mu m in diameter by 30 mm in length in various confluence angles of 45 degrees, 90 degrees, and 135 degrees. Mixing performance of the microchannels was first evaluated via competitive parallel reactions of Villermaux/Dushman. The mixing quality was then described under various total liquid flow rates and initial acid concentration using segregation index (X-s). In the second protocol, mixing performance was further investigated via complicated liquid anti-solvent precipitation (LASP) process for nanodrug production. Curcumin was utilized as a model of an insoluble drug in water and particle size and SEM imaging were then employed to characterize the produced nanosuspentions. The whole results show that despite considerable differences in nature of these two processes, the microchannel with confluence angle of 135 degrees works more efficiently in both protocols, due to its higher mixing quality. (C) 2014 Elsevier B.V. All rights reserved.