Abstract: The reaction chromatographic technique including reaction gas chromato-graphy (RGC), reaction thin layer chromatography (RTLC) and reactionliquid chromatography (RLC) has been reviewed in the present paper. Thistechnique has following advantages: 1) scaled-down sample size to μg levelor less, 2) a minimun loss of material, and 3) free of sample contamina-tion. This method may be used as a potential technique for chemical modifi-cation in mass spectrometry.