KOH solns. with concns. of (i) 0.1 M, (ii) 0.25 M and (iii) 0.5 M as well as (iv) its mixt. (i) with 0.1 M Na4P2O7 soln., mixed in a 1:1 vol. ratio were used to ext. of the sum of humic and fulvic acids and humic acids from peat and lignite. The mass ratio of org. material to extractant was 1:20. In the main, the extractant (ii) was the most effective for both tested materials. Using this extractant for the lignite, the yields of the sum of humic and fulvic acids and humic acids were 47.52 and 46.47%, resp. For the peat, the yields were 29.35 and 27.90%, resp. The extractants (i) and (iv) were the least effective for lignite and peat, resp.