Abstract: Methods to recover acetic acid from diluent aqueous solution, glyoxal and waste water of producing methacrylic acid have been developed. A new process to extract HAc is to use a mixed solvent consisting of tertiary amine and tributyl phosphate. Various factors such as composition of the mixed solvents, concentrations of HAc, (HAc + HNO_3) and (HAc + MAA), contact time, and temperature were studied.The data of liquid-liquid equilibrium have been measured and related. A preliminary discussion of the extractive mechanism is also outlined.