Abstract: There are three space conformations of 2,3-butanediol which coexist in d-,1-, meso- and dl-isomers. It has been reported that the meso- and 1-2, 3-butanediol in grapewine and liquor are quantatively measured by gas chromato-graphy with packed column. The resolving power between the meso- and dl-isomers is less than 0.05 and consequently there is a part overlap between the two peaks3.In this paper the meso- and dl-2, 3-butanediol optical isomers are separated and measured by using a capillary column gas chromatography. The resolving power between meso- and dl-isomers is 1.5 and the heat of solution of dl- and meso-2, 3-butanediol is measured, with △Hdl=-49,0 kJ/mol and △H(?) = - 50.8kJ/mol respectively.Using the gas chromatographic method, we determine the 2,3-butanediol and the ratio of its meso- and dl-isomers formed in pure ethanol which is deaerated with N2 gas and irradiated with γ-rays, β-rays and electric discharges.