Stable concentrated oil-in-water emulsions were prepared from a very viscous Grosmont heavy crude oil in a Sorvall mixer. The viscosity of the concentrated oil-in-water emulsions was minimized by increasing the emulsification temperature, reducing rotational speed of the mixer and using an NaOH dosage well below the total acid number. A pilot plant was designed and built, and a semicontinuous process was developed to produce 45 L batches of concentrated Grosmont oil-in-water emulsions (52-70 vol % crude). With NaOH treatment equivalent to 45% of the TAN, emulsions with oil concentrations up to 65% were Newtonian at shear rates between 200 and 1872 s(-1). Viscosities at 700 s(-1) were close to the predictions of Frankel and Acrivos (1967). Measured turbulent pressure losses in a 0.0211 m diameter tube increased with increasing oil concentration. The specific energy loss, however, decreased with increasing oil concentration. Excellent agreement with von Karman predictions of friction factor was obtained for emulsions with oil concentrations up to 60%. For the 65% emulsions, drag reduction of about 11% was observed. Because of the high viscosity, no turbulent data for the 70% emulsion could be obtained.