Abstract: The phase equilibria of systems containing volatile organic acid (i.e. acetic, propionic, and butyric acids), water and a surfactant (Novel 23-Ethoxylate 2 (N23-E2)) were established at 35°C. This was conducted to evaluate the possible application of N23-E2 as a solvent for the extraction of the acids from aqueous solutions. The thermodynamic consistency of the obtained equilibrium data was tested using the Othmer-Tobias equation/plot and were regressed/fitted to the UNIQUAC, or universal quasi-chemical theory, activity coefficient model. Results indicated that the phase equilibria of the systems studied here can be satisfactorily modeled using UNIQUAC with standard deviation of 3.1%. The obtained data showed that N23-E2 could be used as a solvent for the extraction of butyric acid from aqueous solution. Further equilibrium experiments confirmed that for butyric acid+water+N23-E2 ternary system, 1 hour of incubation at 35°C puts the system at around 95% of the true (established) phase equilibrium and extended periods of shaking did not result to stable emulsion formation that could complicate phase separation. Comparison experiments between other more common surfactants, Tween 80 and Triton X-114, which did not produce two-phase systems, indicated that surfactant properties (i.e. HLB and cloud point) play vital role for the targeted extraction procedure. Finally, economic simulations were conducted using the UNIQUAC model and literature to determine the separation process layout and unit operations. A base case of 1,000 kg/hr feed was assumed with a butyric acid concentration of 6.28% (w/v). Overall, approximately 61% of the incoming butyric acid was extracted and purified into a 98% butyric acid product stream. The net annual revenue however, was an approximate loss of 2 million USD/Year. Recycling of the solvent was briefly investigated to improve the economics and resulted to a profit of 1 million USD/year with a simple payback period of 2.5 years.