A method of coating a substrate by subjecting a surface of the substrate to successive surface reactions of a first precursor and a second precursor according to the principles of atomic layer deposition in a reaction chamber, said reaction chamber comprising a first end having a gas inlet for providing precursor to the reaction chamber; a second end having a gas outlet for discharging precursor from the reaction chamber; a substrate support for holding the substrate; an opposing wall opposite to the substrate support, the substrate support and the opposing wall extending between the first end and the second end; a reaction space inside the reaction chamber defined between the first end and the second end and between the substrate support and the opposing wall; a plasma discharge electrode provided in connection with the opposing wall between the first end and the second end at a first distance ( a) from the first end and at a second distance ( b) from the second end; and a reaction zone provided between the first distance ( a) from the first end and the second distance ( b) from the second end and between the plasma discharge electrode and the substrate support; the method comprising: arranging the substrate to the substrate support in the reaction zone; supplying a predetermined amount of the first precursor via the gas inlet to the reaction chamber for providing a flow of the first precursor to the reaction zone such that the first precursor is depleted by the end of the second end; supplying the second precursor via the gas inlet to the reaction chamber for providing a flow of the second precursor through the reaction zone and discharging the second precursor from the reaction chamber via the gas outlet, the second precursor being inactive to react with the first precursor; generating plasma discharge to the reaction zone with the plasma discharge electrode for forming active precursor radicals from the second precursor supplied into the reaction zone during the flow of the second precursor through the reaction zone, the active precursor radicals being active to react with the first precursor. a first end having a gas inlet for providing precursor to the reaction chamber; a second end having a gas outlet for discharging precursor from the reaction chamber; a substrate support for holding the substrate; an opposing wall opposite to the substrate support, the substrate support and the opposing wall extending between the first end and the second end; a reaction space inside the reaction chamber defined between the first end and the second end and between the substrate support and the opposing wall; a plasma discharge electrode provided in connection with the opposing wall between the first end and the second end at a first distance ( a) from the first end and at a second distance ( b) from the second end; and a reaction zone provided between the first distance ( a) from the first end and the second distance ( b) from the second end and between the plasma discharge electrode and the substrate support; the method comprising: arranging the substrate to the substrate support in the reaction zone; supplying a predetermined amount of the first precursor via the gas inlet to the reaction chamber for providing a flow of the first precursor to the reaction zone such that the first precursor is depleted by the end of the second end; supplying the second precursor via the gas inlet to the reaction chamber for providing a flow of the second precursor through the reaction zone and discharging the second precursor from the reaction chamber via the gas outlet, the second precursor being inactive to react with the first precursor; generating plasma discharge to the reaction zone with the plasma discharge electrode for forming active precursor radicals from the second precursor supplied into the reaction zone during the flow of the second precursor through the reaction zone, the active precursor radicals being active to react with the first precursor. arranging the substrate to the substrate support in the reaction zone; supplying a predetermined amount of the first precursor via the gas inlet to the reaction chamber for providing a flow of the first precursor to the reaction zone such that the first precursor is depleted by the end of the second end; supplying the second precursor via the gas inlet to the reaction chamber for providing a flow of the second precursor through the reaction zone and discharging the second precursor from the reaction chamber via the gas outlet, the second precursor being inactive to react with the first precursor; generating plasma discharge to the reaction zone with the plasma discharge electrode for forming active precursor radicals from the second precursor supplied into the reaction zone during the flow of the second precursor through the reaction zone, the active precursor radicals being active to react with the first precursor.