The effects of high pressure homogenization conditions (pressure, temperature, and hazelnut concentration) on physicochemical properties of hazelnut milks were evaluated, and process parameters were optimized using response surface methodology. Also, the effect of low- and high-temperature heat treatments on properties of hazelnut milk processed according to optimum conditions was investigated. The influence of homogenization pressure was greatest on properties of hazelnut milk followed by hazelnut cake concentration and homogenization temperature within the experimental domain. The optimized experimental conditions for the homogenization of hazelnut milk were 1,140 bar for homogenization pressure, 38.1 degrees C for homogenization temperature, and 12.97% for hazelnut cake concentration. Under optimized conditions, homogenization process was validated by comparing the quality attributes of optimized hazelnut milk with the predicted values, which were between -10.06 and 11.11% of relative error indicated good accordance. Physical and structural properties of samples produced using optimum conditions were slightly affected by heat treatments.