Abstract The present work deals with studying the various factors affecting the stability and viscosity of a surfactant-stabilized viscous crude-oil-in-water emulsion for pipeline transportation. The study revealed that the stability of the oil-in-water emulsion stabilized by an anionic surfactant increases as the surfactant concentration increases with a subsequent decrease in the crude-oil-water interfacial tension. Increasing the oil content, the speed and the temperature of mixing of the emulsion resulted in an increased emulsion stability. The maximum sodium chloride concentration in the aqueous phase of the emulsion, above which surfactant precipitation occurred, was 1M at a surfactant concentration of 0.5% in the aqueous phase. For all sodium chloride concentrations of less than 1M, no emulsion resolution took place. The viscosity of the studied Geisum-crude-oil-in-water emulsion was decreased by decreasing the oil content and the speed of mixing and increasing the temperature. The pour-point values for oil-in-water emulsions having different oil contents were always less than those of the Geisum crude oil. Demulsification of the stable crude-oil-in-water emulsion was achieved by treatment with 60 ppm alkyl phenolformaldehyde oxyalkylated chemical demulsifier at 50°C.