Lignite was leached with H(2)O and aq. solns. of KOH, NH(3), H(3)PO(4), HNO(3), EDTA, diethylenetriaminopentaacetic acid and Na tripolyphosphate at room temp. for 14 days to sep. humic acids and modify the lignite structure. The leaching with KOH was most efficient. The products were considered as components of fertilizers.