A flucarbazone sodium hemihydrate method and composition. A method of suppressing growth of grass and broadleaf weeds is described including applying to said weeds at least one dust-free composition comprising flucarbazone sodium-hemihydrate as an active ingredient. A method for preparing flucarbazone sodium-hemihydrate is also described including treating 4,5-dihydro-3-methoxy-4-methyl-5-oxo-N-[[2-(trifluoromethoxy)phenyl]sulfonyl]-1H-1,2,4-triazole-1-carboxamide (MSU) with aqueous sodium hydroxide under pH-controlled conditions; and confirming that a hemihydrate flucarbazone sodium has been obtained.