Nowadays consumers are looking for food products which are useful for human health in addition to satiate their hunger. The term “functional food” refers to food containing one or several nutrients with specific beneficial functions in the human body. It is recently proven that some fats and oils in addition to having nutritional value have positive effects on the human body. One of the functional lipid compounds is conjugated linoleic acid (CLA). The aim of this study is to prepare a functional beverage containing CLA as a functional compound. Because CLA has a low water-solubility and beverages are mainly composed of water, in order to add CLA to beverage oil -in -water emulsion can be used which is called beverage emulsion. Beverage emulsions are thermodynamically unstable systems and tend to break down due to various physicochemical mechanisms during storage. Emulsions composed of arabic gum (AG) (5-10% w/w), CLA oil (3.5-6.5% w/w) and xanthan gum (XG) (0.1-0.3% w/w) were prepared and their mean droplet size (D 43 ), opacity, speci?c gravity, viscosity and heat stability was investigated applying response surface methodology (RSM). The effects of main emulsion components were evaluated and results revealed that their contents had a direct impact on physicochemical characteristics of emulsions. It was generally concluded that the increase in AG and XG content led to increase in density, turbidity, viscosity and stability. D 43 decreased when AG concentration increased and increased by the XG content. The oil content has resulted in increasing D 43 and turbidity whereas was negatively effective on heat stability and specific gravity. Applying RSM, emulsion with the highest specific gravity, turbidity, viscosity, stability and smallest average droplet size considered as an optimum product. Optmization based on D-optimal design was succesfully accomplished for selecting a CLA oil in water beverage emulsion containing 3.5% w/w oil, 10%AG w/w and 0.3% w/w XG as an optimum formula. The emulsion and finished product stability and oxidative stability were investigated during 49 days of storage and results showed that specific gravity and viscosity decreased insignificantly during this time. Opacity, heat stability, specific surface area and creaming index decreased significantly and surface tention, pH, size index, D 43 and span increased in the passage of time. Peroxide value increased until the day 21 and began to fall down after that time. TBA and Totox values increased significantly during storage time. Turbidity of finished product decreased significantly and turbidity loss rate was calculated 0.038 A/day which was low and indicated the good stability of diluted form.Totally, the oxidative stability of the CLA-beverage emulsion and its stability in beverage were acceptable upto 28 days and 21 days, respectively. Keywords : Arabic gum, Xanthan, Conjugated linoleic acid, Emulsion beverage, Functional, Optimization, Oxidative stability