The objective of this study was to identify suitable combinations of additives to aqueous alkaline formulations for the potential recovery of Saskatchewan heavy crude oil. A previously developed strategy was applied to screen various additive combinations consisting of three commercial petroleum sulfonate surfactants and two commercial lignosulfonate surfactants. The selection of the additives was based on a large number of physical and interfacial property measurements in conjunction with phase stability tests at different temperatures. The resulting ternary formulations, labelled here as Mixed-Surfactant-Enhanced Alkaline (MSEA) systems, were very successful in reversing the trend of increasing interfacial tension with time that characterizes additive-free alkaline/crude oil systems. This success came at the expense of initial IFT values that were considerably higher than those exhibited by the corresponding additive-free alkaline solutions. However, at higher temperatures (65-degrees-C), these ternary MSEA formulations were capable of generating very low IFT values against the crude oil (in the range of 5 x 10(-2) to 10(-1) mN/m), which suggests that they could be suitable candidates for commercial exploitation of heavy oil recovery processes.