Abstract: Ion chromatography is a widely used technique to analyse ice cores for ions like Na+, NH4+, K+, Mg++, Ca++, F-, MSA-, Cl-, NO3- and SO4-- that are present in polar ice cores at ppb level. By using sample preconcentration and an optimised separation technique we have been able to detect Li+ in ice core samples in concentrations as low as 0.0001 meq·kg-1 or 0.7 ppt by ion chromatography. During routine analysis of ions in ice cores, the lithium content has been evaluated and recorded. The IC technique used in these measurements and some exemplary IC data from the GRIP (Greenland Ice Core Project) and the NGRIP (North Greenland Ice Core Project) ice cores will be presented. By these data we introduce Li+ concentration as a new parameter in the analysis of ice cores.Like other ions Li+ reflects climatic changes and shows seasonal cycles. On the basis of the geochemistry of lithium we suggest that Li+ measured in the Greenland ice cores is derived from mineral dust. However data from the NGRIP ice core that represents the 8.2 ka BP Holocene cold event show a strong Li+ signal that does not correlate with any other ionic component measured. This means that the lithium content in ice cores is a signal with its own pattern, which is not yet understood.