The formation of emulsions is a critical application that interests many industrial fields. Among the various interests to produce emulsions, this work focuses on the emulsification of water in fuels, in order to improve combustion and reduce emission of harmful gases. The manufacturing process of these emulsions must meet a number of constraints such as water fraction, mean droplet size, delivered flow rate and process energy consumption. Among possible techniques, this study focuses on the implementation of crossing microchannels. For this purpose, two geometries of the cross section of the channels have been tested. The implementation of several flow configurations has also been investigated. Other parameters were varied such as the variation of the ratio of flow rates of lipid phase and water, the nature and content of surfactant. In conclusion, obtaining emulsions of water in oil having a mean droplet size of about 4 lm was possible with several operating conditions. Channel geometry and flow pattern have a significant influence on the possibility of forming this type of emulsions. (C) 2012 Elsevier Ltd. All rights reserved.