Abstract The construction and characteristics of an argon triode-type detector designed for gas chromatography in which nickel-63 is used as the ionization radiation source are described. The detector can operate at temperatures up to 400°. Measurements showing the influence of the dimensions of the electrodes on the characteristics of the detector are presented. Using these results, a detector was developed in which the third electrode current depends minimally on the temperature, carrier and secondary gas flow-rates and voltage. The base current of the third electrode was about 100 times lower than the argon detector base current. The detectivity of the detector is 10 −12 g/cm 3 for benzene and n-pentane in argon. Investigations of the electric field distribution inside the detector are described and conclusions concerning the possibility of building an argon triode-type detector with different triode and anode shapes are drawn.