The present invention pertains to the construction of analytic instruments and can be used for analysing natural and industrial water, biological samples, geological samples and air. The purpose of this invention is to reduce substantially the power used by the atomiser and the analyser, and to increase the number of objects that can be analysed. To this end, the method for the thermionic atomisation of a sample involves carrying out an ionic sputtering of the sample from the cathode in a low-pressure discharge. The cathode is heated by the discharge to a temperature of between 800 and 1400 DEG C, while the ballast gas consists of Kr or Xe under a gas pressure of 10 to 15 torrs. The thermionic atomisation device includes an atomiser arranged in a gas-discharge chamber filled with an inert gas. The atomiser is made in the form of a hollow, cylindrical, metallic and thin-wall cathode. In order to reach this goal, the method involves using a thermionic atomisation device which, in an efficient embodiment, consists of the above-mentioned gas-discharge atomiser, i.e. a hollow, metallic and thin-wall cathode. This mechanism enables the sputtering and atomisation of the sample in a short time (0.2 to 1 sec.), thus lowering the detection limits while eliminating matrix effects.