A method for the preparation of 1,2-propanediol comprising the steps: a) reacting propene with hydrogen peroxide at a temperature of from 50 to 110 °C in the presence of a catalyst mixture comprising a phase transfer catalyst and a heteropolytungstate in a liquid reaction mixture comprising an aqueous phase with a maximum apparent pH of 6, wherein the term "apparent pH" here refers to a value determined by measurement with a glass electrode employing a commercial pH meter calibrated with aqueous buffer solution of known pH for measuring dilute aqueous solutions, and an organic phase comprising an alkylaromatic hydrocarbon solvent; b) separating the reaction mixture obtained in step a) into an aqueous phase (P a) comprising 1,2-propanediol and an organic phase (P o) comprising non-reacted propene, the alkylaromatic hydrocarbon solvent and dissolved oxygen from hydrogen peroxide decomposition; c) contacting the organic phase (P o) separated in step b) with a stream of a non-flammable gas at a flow rate of non-flammable gas, a temperature and a pressure effecting desorption of from 10 to 75 % of the oxygen dissolved in the organic phase (P o) into the stream of non-flammable gas, providing an oxygen depleted organic phase (P d) and an off-gas comprising the non-flammable gas and desorbed propene and oxygen; d) recycling at least a part of the oxygen depleted organic phase (P d) to the reaction step a); and e) recovering 1,2-propanediol from the aqueous phase (P a); wherein the mass ratio of alkylaromatic hydrocarbon solvent introduced to step a) to hydrogen peroxide introduced to step a) is from 4:1 to 30:1 and steps a) and b) are carried out in vessels flooded by the liquid reaction mixture at a pressure high enough to suppress desorption of gas from the liquid reaction mixture. a) reacting propene with hydrogen peroxide at a temperature of from 50 to 110 °C in the presence of a catalyst mixture comprising a phase transfer catalyst and a heteropolytungstate in a liquid reaction mixture comprising an aqueous phase with a maximum apparent pH of 6, wherein the term "apparent pH" here refers to a value determined by measurement with a glass electrode employing a commercial pH meter calibrated with aqueous buffer solution of known pH for measuring dilute aqueous solutions, and an organic phase comprising an alkylaromatic hydrocarbon solvent; b) separating the reaction mixture obtained in step a) into an aqueous phase (P a) comprising 1,2-propanediol and an organic phase (P o) comprising non-reacted propene, the alkylaromatic hydrocarbon solvent and dissolved oxygen from hydrogen peroxide decomposition; c) contacting the organic phase (P o) separated in step b) with a stream of a non-flammable gas at a flow rate of non-flammable gas, a temperature and a pressure effecting desorption of from 10 to 75 % of the oxygen dissolved in the organic phase (P o) into the stream of non-flammable gas, providing an oxygen depleted organic phase (P d) and an off-gas comprising the non-flammable gas and desorbed propene and oxygen; d) recycling at least a part of the oxygen depleted organic phase (P d) to the reaction step a); and e) recovering 1,2-propanediol from the aqueous phase (P a);