A mini reactor with 16 channels and with channel diameter of I mm or 2 mm is designed, fabricated and studied experimentally. Two fluids are divided into 16 channels through distributor, then contacted at T-mixers, and finally collected. Both distributor and collector are designed following the arborescent shape. Visualization with pH indicator bromothymol blue (BTB) is used to qualitatively observe the global mixing; while for the micromixing performance assessment, we used competitive iodide/iodate (Villermaux/Dushman) reactions. Segregation index and micromixing time, with respect to energy dissipation rate are used to characterize micromixing performance. Visualization with pH indicator shows that complete global mixing at the collector by liquid impingement is obtained under our tested conditions. Iodide/iodate reaction shows a rapid mixing at molecular level as the flowrate increases and impingement being enhanced. Micromixing time estimated by IEM (Interaction by Exchange with the Mean) model is compared with other micro-structured mixers in the literature. Comparable mixing performance is obtained using our millimetric reactor with that of micro-structured designs. The design of multi-channel reactor with arborescent distributor and collector makes possible the numbering-up of multiple channels. Process intensification is highlighted by high throughput and compact size, thus may be attractive for industrial application. (C) 2012 Elsevier B.V. All rights reserved.