Abstract As CO2 is a universal product of living organisms, the measurement of CO2 evolution is important for analyzing biological activity. Recently, the use of an infrared gas analyzer (IRGA) for CO2 measurement has facilitated the assessment of soil biological activity, especially under laboratory conditions. The IRGA method for CO2 measurement is more convenient than the methods using an alkaline absorbent, in terms of sensitivity and speed. In this paper, an automatic set-up using IRGA and a personal computer for continuous measurement of CO2 evolution from multiple samples is described.