ABSTRACTSData are presented for the osmotic pressures of commercially available lime, lemon, prune, carrot and salted and unsalted tomato juices and their concentrates. Similar data are presented for sucrose‐water and glucose‐sucrose (mole ratio 10:1)‐water solutions in the temperature range 7.5–25°C. The effects of the temperature on parameters of process design show that by operation at a lower temperature it is possible to obtain a higher recovery of aroma compounds in the concentrate in the second stage reverse osmosis treatment of fruit juice water obtained from the first stage treatment. This possibility is confirmed by the experimental results at 7.5°C and 25°C.