This paper presents the development of a novel parallel minichannel contactor for monodisperse water-in-oil emulsification. The novel contactor having 16 Y-junctions in parallel equipped with multi-scale tree-like fluid distributor and collector was realized and experimentally tested. Oils with different physical properties and water were used as continuous phase and dispersed phase, respectively. Influences of different factors including the parallelization, the water/oil flow-rate ratio and two-phase physical properties on the two-phase flow characteristics and on the coefficient of variation were studied and discussed. Results showed that for water-pure oil flow, the novel parallel minichannel contactor is capable of producing monodisperse water-in-oil emulsions with high throughput and low energy consumption under our tested conditions. The Ohnesorge number (Oh) has a significant influence on the emulsion monodispersity and the capillary number (Ca) appears as a proper indicator for liquid-liquid break-up regimes. A predictive correlation for the Oh number was proposed by fitting the experimental data obtained in the study. (C) 2017 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.