Emulsification step of flaxseed oil microencapsulation was optimized using the Box-Behnken design of the response surface methodology in wall material concentration, oil loading and ultrasonic emulsification time. The optimization was performed to optimize the microencapsulation efficiency (MEE) and product yield (PY). Bulk density, particle size and hygroscopicity of the microcapsules were additionally determined. MEE showed a positive correlation with wall material concentration and ultrasonication time; however, increasing oil loading had an adverse effect. PY was mainly affected by wall material concentration and increasing the wall material concentration resulted in lower product yield. Longer ultrasonication time decreased particle size of the flaxseed oil emulsion, but particle size of the microcapsules did not significantly change. The particle size of the microcapsules was increased by increasing wall material concentration. Optimum conditions for the microencapsulation of flaxseed oil were predicted as a wall material concentration of 20 g.100 g(-1), an oil loading of 20 g oil.100 g(-1), wall material and an ultrasonication time of 120 s and this conditions provided 92.4% MEE and 68.7% PY. For practical conditions, wall material concentration of 20 g.100 g(-1), oil loading of 35.1 g oil.100 g(-1) wall material and ultrasonication time of 120 s can be suggested in the flaxseed oil microencapsulation process. (C) 2014 Elsevier B.V. All rights reserved.