The present study investigates electrochemical ozone dissolved water production (EOP) without O-3 gas emission using a new EOP system and external gas-liquid mixers. The target gas-phase O-3 formation rate was set to less than 0.01 mL/min. Regression analysis was performed using test matrix data obtained from EOP experiments. The regression analysis of the current efficiency of gas-phase O-3 formation Phi(g) [%] using the anolyte flow rate V [L/min], current density I [A/cm(2)], and cross term I/V gave a high determination coefficient of R-2 = 0.9965. Ozone dissolved water with an O-3 concentration higher than 2 mg/L was obtained without using external mixers at the rates of 2.2-2.7 L/min. The O-3 concentration was doubled to 4 mg/L by the use of external mixers. The mixers can efficiently increase the ratio of dissolved ozone to total produced ozone in anolyte and decrease the O-3 gas formation rate to one-tenth of that without mixers. The bypass operation experiment revealed that ozone dissolved water with an O-3 concentration higher than 2 mg/L can be produced at a rate of 6 L/min. The concentration of O-3 gas emitted into a closed space exceeded the regulation value of 0.1 mL/m(3). However, that into an open space was lower than the regulation value when the dissolved O-3 concentration was less than 2.7 mg/L.