YCH-1 analyzer is haled on coulomctric electrolysis by which small amounts of water and carbon dioxide in rocks and minerals can be determined simultaneously. A small quartz combu-stion tube was used for igniting the sample. The tube was filled with AgMnO4 which caa remov sulfur and halogens during ignition. Nitrogen was used as carrier gas. The carbon dioxide evolved was inrtoduced into a tube containinn specially prepared lithium hydroxide and an equivalent amount of water was displaced and then determined. The electrolytic cell was made of special materials. Electrolysis currents were automatically integrated by calibrated voltage to frequency and pulse counters. The absolute standard deviations were less than 0.1% for 8 determinations of 1.89-2.11 % of H2O and 5.45-5.79 %of CO2.