A filling machine, in particular for filling a container with a pasteurized liquid, comprising: • a gas line; • a liquid supply line, adapted to be connected to a liquid tank; • at least one filling device comprising: a) an inlet, communicating with said liquid supply line to receive a liquid stored in said liquid tank; b) a lower outlet, for supplying the liquid into said container during filling; c) a gas port, communicating with said gas line and defining a gas outlet for letting gas flow out of the container towards said gas line during filling; • pressure sensor means connected to said gas line and to said liquid supply line to determine a feedback value defined by the pressure difference between said liquid supply line and said gas line; • an electronic control unit configured to bring the pressure difference between said liquid supply line and said gas line to a set-point in response to said feedback value; the machine further comprising: • a gas tank, which permanently communicates with said gas line and is separated from said liquid supply line; • first valve means to put said gas tank in communication with a pressurized gas source; • second valve means arranged between said gas tank and a discharge opening; characterised in that opening of said first valve means is controlled by said electronic control unit to increase pressure inside said gas tank; and in that said electronic control unit is configured to open said second valve means so as to discharge gas from said gas tank when said feedback value becomes lower than said set-point. • a gas line; • a liquid supply line, adapted to be connected to a liquid tank; • at least one filling device comprising: a) an inlet, communicating with said liquid supply line to receive a liquid stored in said liquid tank; b) a lower outlet, for supplying the liquid into said container during filling; c) a gas port, communicating with said gas line and defining a gas outlet for letting gas flow out of the container towards said gas line during filling; a) an inlet, communicating with said liquid supply line to receive a liquid stored in said liquid tank; b) a lower outlet, for supplying the liquid into said container during filling; c) a gas port, communicating with said gas line and defining a gas outlet for letting gas flow out of the container towards said gas line during filling; • pressure sensor means connected to said gas line and to said liquid supply line to determine a feedback value defined by the pressure difference between said liquid supply line and said gas line; • an electronic control unit configured to bring the pressure difference between said liquid supply line and said gas line to a set-point in response to said feedback value; the machine further comprising: • a gas tank, which permanently communicates with said gas line and is separated from said liquid supply line; • first valve means to put said gas tank in communication with a pressurized gas source; • second valve means arranged between said gas tank and a discharge opening; characterised in that opening of said first valve means is controlled by said electronic control unit to increase pressure inside said gas tank; and in that said electronic control unit is configured to open said second valve means so as to discharge gas from said gas tank when said feedback value becomes lower than said set-point.