Abstract A method for the preparation of carrier-free fluorine-18 using a column of hydrous stannic oxide is described. The adsorption and desorption characteristics of the fluoride ion on the column has been investigated using F-18 as a tracer. The present study has confirmed that the fluoride ion is practically completely adsorbed on the column in a slightly acid medium and can be subsequently eluted from the column with an alkaline solution. Though the efficiency of desorption of the fluoride ion increases with increasing concentration of alkaline solution, a moderate concentration (about 0.3 N) is considered to be suitable for practical uses. A simple and effective procedure for the preparation of carrier-free F-18 from neutron-irradiated lithium carbonate is proposed. The chemical yield is about 75% and the separation time can be as short as 20 min. The content of tritium in the product does not exceed 0.5% of the F-18 activity and that of tin and lithium is less than 1.5 ppm.